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THE  MICROSCOPICAL 

EXAMINATION  OF  POTABLE 

WATER. 


GEO.    W.  RAFTER, 

MEMBER  OF  THE  ROCHESTER  ACADEMY  or  SCIENCE. 


SECOJSTID    EIDITIOIST. 


NEW  YOEK : 

D.  VAN   NOSTRAND   COMPANY,    PUBLISHERS, 

23  MURRAY  AND  27  WAEEEN  STREETS. 

1900. 


COPYRIGHT,  1892, 
BY  D.  VAN  NOSTRAND  Co. 


C.  J.  PETERS  &  SON, 
TYPE-SETTERS  AND  ELECTROTYPE 
145  HIGH  ST.,  BOSTON. 


PREFACE. 


THE  publishers  of  the  SCIENCE  SERIES  having 
asked  the  writer  to  prepare  a  monograph  on  the 
Microscopical  Examination  of  Potable  Water,  I 
will  endeavor  to  comply;  though  that  a  civil  engi- 
neer should  be  expected  to  prepare  anything  of 
value  on  a  subject  which  has  engaged  the  attention 
of  the  most  eminent  chemists  and  biologists  is 
something  of  a  surprise.  Possibly,  however,  the 
fact  that  studies  in  this  direction  have  occupied 
my  leisure  hours  for  a  number  of  years,  and  have 
led  to  the  production  of  a  number  of  more  or  less 
useful  papers  thereon,  may  be  to  some  extent  an 
explanation;  but  it  is  sincerely  hoped  that  the 
expectations  of  neither  publishers  nor  readers  will 
be  raised  too  high. 

This  little  book  has,  it  is  believed,  one  merit 
frequently  absent  in  formal  works  of  more  preten- 
sion. It  may  be  taken  as  fairly  representing  the 
state  of  the  art,  of  which  it  professes  to  treat,  at 
the  date  of  issue,  namely,  at  the  beginning  of  the 
year  1892;  that  this  is  a  real  merit  will  be  appre- 
ciated by  every  serious-minded  student  who  has 
3 


had  occasion  to  travel  in  new  roads.  To  all  such 
who  may  be  interested  in  the  advancement  of  pub- 
lic sanitation  this  monograph  is  presented,  albeit 
somewhat  hesitatingly,  in  the  hope  that  it  may 
be  of  essential  use  in  actual  work. 

The  perfected  method  of  making  the  quantita- 
tive enumeration  of  the  microscopical  organisms 
in  potable  water,  which  is  here  described,  is  the 
joint  work  of  Prof.  William  T.  Sedgwick  and  my- 
self, though  both  Mr.  A.  L.  Kean  and  Desmond 
FitzGerald,  C.  E.,  have  contributed  useful  ideas. 
To  Professor  Sedgwick  must,  however,  be  assigned 
the  credit  of  working  out  a  really  practical  method 
of  making  these  examinations,  and  to  him  must 
be  assigned  the  honor  of  giving  the  method  a 
name.  The  author  took  the  method,  as  will  be 
shown  in  the  body  of  the  volume,  after  Professor 
Sedgwick  had  put  it  on  a  working  basis,  and  added 
certain  refinements  of  technique.  Professor 
Sedg\Vick  has  deemed  these  refinements  of  suffi- 
cient value  to  justify  coupling  the  author's  name 
with  his  own,  and  has  accordingly  described  it  in 
the  Massachusetts  Health  Reports  as  the  Sedg- 
wick-Rafter  method.  This  I  acquiesce  in,  though 
the  statement  may  be  made,  that  a  complete  bal- 
ancing on  my  part  of  the  account  between  the 
biologists  of  the  Massachusetts  State  Board  of 
Health  and  myself,  would  show  on  the  whole 
transaction  a  considerable  amount  still  to  the 
credit  of  that  Board. 

In  preparing  this  monograph.  I  have  assumed 


that  the  reader  possesses  a  fairly  complete  knowl- 
edge of  the  optical  part  of  the  microscope  and  of 
micrometric  measurements.  On  these  heads, 
therefore,  only  such  information  is  given  as  is 
necessary  to  elucidate  the  special  work  in  hand. 
In  the  same  way  the  technique  of  collecting,  pre- 
serving, and  mounting,  as  treated  in  Part  I.,  have 
been  only  briefly  given.  The  full  detail  leads  too 
far  away  from  the  special  subject.  Those  not 
possessing  the  necessary  preliminary  information, 
and  still  wishing  to  fit  themselves  for  an  intelligent 
use  of  the  method,  may  find  abundant  references 
to  standard  literature  of  the  microscope,  either  in 
the  explanatory  foot-notes  or  at  the  end  of  the 
volume. 

In  the  same  way  a  knowledge  of  the  funda- 
mental ideas  in  relation  to  modern  water  analysis 
is  assumed  on  the  part  of  the  reader.  Those  who 
do  not  fully  possess  such  knowledge  can  hardly  do 
better  than  to  consult  the  recent  Special  Keports 
of  the  Massachusetts  State  Board  of  Health. 

G.  W.  R. 
ROCHESTER,  JST.Y.,  Dec.  24,  1891. 


NOTE.  —  The  small  figures  throughout  the  text, 
thus :  MacDonald's  Water  Analysis,14  refer  to 
the  number  of  the  volume  cited  in  the  list  of 
literature  following  Part  II. 


MICROSCOPICAL  EXAMINATIONS, 


PART   I.—  QUALITATIVE. 

How  to  Study  the  Biology  of  a  Water 
Supply. 

OTHER  things  being  equal,  there  is  in 
every  community  having  a  public  water 
supply,  a  relation  between  the  degree  of 
purity  of  such  supply  and  the  public 
health.  Indeed,  it  may  be  broadly  stated, 
that  in  a  community  with  a  water  supply 
of  a  high  standard  of  purity,  there  will  exist 
a  lower  death-rate  than  if  the  standard  of 
purity  be  materially  lower. 

No  argument  is  necessary,  then,  to  estab- 
lish the  proposition,  that  information  rela- 
tive to  the  biology  of  a  public  water  supply 
is  of  vast  importance,  both  to  individuals 
and  communities;  and  a  study  having  for 
its  object  the  solution  of  biological  prob- 
lems may  be  safely  counted  as  worthy  of 
intelligent  effort. 

7 


WORKING-TOOLS. 

For  the  general  study  of  the  biology  of 
a  water  supply  certain  handy  tools  are  req- 
uisite. 

These  are  the  compound  microscope, 
fitted  with  about  the  following  list  of  ob- 
jectives :  one-inch,  one-half  inch,  or  four- 
tenths,  one-fourth,  and  one-eighth.  The 
one-half  and  the  one-fourth  inch  are  the 
most  useful.  A  one-half  inch  Gundlach, 
of  50°  angular  aperture,  and  a  one-fourth 
inch  Bausch  &  Lomb  professional,  of  110° 
^angular  aperture,  have  been  found  satisfac- 
tory. For  this  work  the  moderate-angled 
objectives  are  preferred  to  those  of  wider 
angle.  They  have  better  working  distance 
than  the  wide-angled  lenses  of  recent  make. 
The  one-inch,  one-fifth  inch,  and  one-eighth 
inch  are  sometimes  used,  but  the  use  of 
these  latter  is  infrequent  compared  with  the 
two  above  mentioned ;  and  it  may  be  said,  in 
passing,  that  a  very  complete  study  of  the 
biology  of  a  water  supply  can  be  made  with 
only  two  objectives;  namely,  the  one-half 
inch  and  the  one-fourth.  In  studying  sup- 


plies  containing  many  of  the  larger  forms, 
such  as  Hydra,  Cyclops,  Daphnia,  Diopta- 
mus,  etc.,  either  a  two-inch,  or  one  and  one- 
half-inch  would,  however,  be  very  conven- 
ient. 

While  thus  somewhat  radical  in  express- 
ing a  preference  for  moderate-angled  object- 
ives for  ordinary  work,  it  is  but  fair  to 
say  that  for  the  highest  class  of  biological 
work  wide-angled  objectives  are  nearly 
indispensable.  For  any  immersion  object- 
ive above  one-sixth  inch  focal  distance,  one 
should  purchase  those  of  large  angular  aper- 
ture. There  is,  however,  in  all  such  object- 
ives, a  considerable  sacrifice  of  working 
distance  to  aperture,  so  that  the  specific  use 
to  which  an  objective  is  to  be  put  must  to  a 
great  extent  determine  what  to  purchase. 
Of  one  thing  we  may  be  certain,  that  the 
very  wide-angled  immersion  lenses  require 
a  perfection  of  movement  in  the  micro- 
scope stand,  and  a  delicacy  of  manipulation, 
which  add  considerably  to  the  amount  of 
time  required  to  complete  an  examination ;  * 

*  For  very  high-power  objectives,  cover  glasses,  even  of 
t'.:c  thinest  glass,  are  too  thick,  and  ordinary  talc  split  into 


10 


so  that  for  the  working  microscopist  to 
whom  time  is  of  value,  the  question  of  just 
what  shall  be  the  limit  is  an  important 
one. 

Of  eye-pieces  one  is  indispensable,  and 
two  or  more  are  desirable.  Where  only 
two  are  purchased,  they  should  be  one  of 
an  inch,  and  one  of  an  inch  and  a  half  focal 
distance.  The  Huyghenian  eye-piece  gives 
somewhat  clearer  definition  than  the  peri- 
scopic,  but  the  periscopic  has  the  advan- 
tage of  doubling  the  field.  A  fairly 
complete  battery  would  consist  of  a  one- 
inch  periscopic,  in  addition  to  the  two 
Huyghenian  eye-pieces  above  suggested. 

LIFE-CAGES    AND    CULTURE-CELLS. 

The  catalogues  are  filled  with  life-cages, 
growing  and  culture  cells  of  divers  and 
various  sorts,  and  the  beginner  in  biology 
is  likely  to  conclude  that  considerable  ex- 
thin  laminae  may  be  used.  W.  Saville  Kent,  in  his  "  Manual 
of  the  Infusoria,"  speaks  of  using  laminae  of  such  extreme 
tenuity  that  they  may  be  blown  away  with  the  lightest 
touch.  With  such  films  Kent  says  the  investigation  of 
the  infusoria,  with  1-16,  1-25,  or  even  1-50  inch  objectives, 
becomes  a  comparatively  easy  task. 


11 


penditure  is  necessary  for  apparatus  of 
this  sort.  The  author's  experience,  after 
trial  of  the  various  life-slides  and  life-cages, 
is  that  for  ordinary  examination^  a  plain 
slide,  with  a  ring  of  cement  forming  a 
shallow  cell,  covered  with  a  cover  glass,  is, 
on  the  whole,  preferable.  Holman's  siphon- 
slide  and  Holman's  siphon  life-cage  are  of 
use  where  it  is  desired  to  observe  the  same 
object  continuously  for  several  days.  Their 
expense,  however,  is  considerable,  and 
fairly  satisfactory  results  may  be  gained 
with  the  following  device,  which  has  the 
merit  of  costing  almost  nothing.  A  plain 
glass  slip  is  taken,  and  to  one  side  of  it  two 
three,  four,  or  more  thicknesses  of  chemi- 
cal filter  paper  are  pasted,  the  number 
of  thicknesses  depending  upon  the  depth 
of  cell  required.  The  cell  is  made  by 
cutting  out  the  centre,  either  round  or 
square,  according  to  the  taste  or  fancy  of 
the  operator.  In  this  cell  is  deposited  the 
organism  which  it  is  desired  to  study. 
The  placing  of  a  cover  glass,  and  the  secur- 
ing of  it  with  a  little  cement,  completes 
the  operation  so  far  as  the  construction  of 


12 


the  growing-cell  is  concerned.  The  cell  is 
placed  upon  the  stage  of  the  microscope, 
and  supplied  with  water  by  a  rubber  tube, 
acting  as  a  siphon,  from  a  jar  standing  on 
a  shelf  above  the  stage.  The  supply  of 
water  is  controlled  by  a  brass  cock  placed 
at  the  lower  end  of  the  rubber  siphon  tube, 
set  so  as  to  allow  water  to  drop  very  slowly 
upon  the  paper  composing  the  cell,  just 
outside  the  edge  of  the  cover  glass. 

In  preparing  such  a  cell,  care  should  be 
taken  to  cement  the  several  layers  of  the 
paper  together  at  the  inner  edges,  in  order 
to  prevent  the  more  minute  objects  from 
passing  in  between  the  layers.  In  using 
it,  the  slide  should  be  dipped  in  water, 
thoroughly  wetting  the  paper  before  filling 
the  cell,  and  the  delivery  of  water  from 
the  siphon  brought  to  such  a  rate  as  to 
keep  the  paper  constantly  wet,  just  sup- 
plying the  loss  from  evaporation.  The 
best  results  will  be  obtained  by  setting  the 
microscope  vertically.  Filter  paper  is  used 
in  its  construction,  in  order  to  insure  that 
the  paper  contains  nothing  likely  to  kill 
the  object  whose  life-history  it  is  desired 


13 


to  study.  For  deeper  cells  the  best  quality 
of  white  cotton  blotting-paper*  may  be 
used,  the  precaution  having  been  taken 
to  soak  it  for  several  days  in  frequent 
changes  of  pure  water.  For  low-power 
objectives  this  cell  may  be  constructed  of 
two  thin  slides,  with  a  layer  of  blotting- 
paper  between  them,  the  slides  held  in 
place  by  rubber  bands  at  the  ends. 

Recklinghausen's  growing  cell  f  is  stated 
by  Frey  to  be  an  efficient  device  for  pre- 
venting the  evaporation  of  fluids.  It 
consists  of  a  glass  ring  cemented  to  an 
ordinary  slide,  forming  a  cell,  in  which 
the  organism  to  be  examined  is  placed  in 
a  little  water.  Blotting-paper  is  folded 
over  the  edges  of  the  glass  ring,  and  a  tube 
of  thin  rubber  slipped  over  this,  and  con- 
nected with  the  objective,  being  held  in 
place  by  compression  bands.  Around  the 
outside  of  the  glass  cell  several  thicknesses 
of  moist  blotting-paper  are  wrapped,  and 

*  Such  a  quality  of  blotting-paper,  which  is  claimed  to 
be  entirely  free  from  chemicals,  and  composed  of  nothing 
but  pure  cotton  fibre,  may  be  obtained  from  the  stationers. 

t  Frey,  on  Microscopes  and  Microscopical  Technology,90 
p.  «,H). 


14 


to  these  additional  moisture  occasionally 
added. 

For  studying  the  life-history  of  very 
minute  organisms,  an  efficient  cell  may 
also  be  made  by  inverting  a  cover  glass 
over  a  glass  cell,  with  a  little  water  at  the 
bottom,  the  organism  to  be  studied  being 
contained  in  a  drop  of  liquid  on  the  under 
side  of  the  cover  glass. 

The  moist  chamber  used  by  Dallinger 
and  Drysdale  in  their  investigation  of  the 
monads  is  of  interest  and  value,*  and  illus- 
trations of  it  can  be  found  in  Kent's  "Man- 
ual of  the  Infusoria." 

Maddox's  growing  slide  is  also  worth 
trial.  Carpenter  is  a  convenient  reference 
for  a  description.! 

Weber's  annular  cell  is  an  American  in- 
vention, and  worth  trial.f 


*  This  cell  was  originally  illustrated  in  Monthly  Micro- 
scopical Journal  for  March,  1874. 

t  "  The  Microscope  and  its  Revelations,"  by  Wm.  B. 
Carpenter,  sixth  edition,  p.  145.8R  Originally  described 
by  Dr.  Maddox  in  his  paper  on  Cultivation  of  Fungi,  in 
Monthly  Microscopical  Journal  for  1870,  vol.  iii. 

$  Carpenter,  loc.  cit.,  p.  147. 


15 


SUB-STAGE    CONDENSER. 

For  assisting  the  illumination,  a  good 
sub-stage  condenser  is  at  the  present  day 
indispensable,  and  of  the  several  forms  the 
Abbe  may  be  considered  the  best.  It 
admits  of  the  greatest  range  of  adjustment 
without  loss  of  time ;  and  when  it  is  desired 
to  examine  an  object  under  all  conditions 
of  illumination,  this  is  a  matter  of  con- 
siderable importance.  It  is  provided  with 
a  swinging  ring  carrying  diaphragms  of 
various  apertures.  The  blue  glass  which 
accompanies  it,  for  furnishing  monochro- 
matic light  when  working  by  lamplight, 
is  also  of  value.*  By  its  use  the  objection- 
able and  trying  yellow  glare  of  lamplight 
is  entirely  obviated;  and  if  one  works  by 
lamplight,  a  considerably  larger  amount  can 
be  done  without  over-fatiguing  the  eye  than 
can  possibly  be  accomplished  without  it. 
The  value  of  the  condenser  may  be  readily 
shown  by  a  trial  of  it  on  one  of  the  test 

*  The  opticians  also  furnish  a  blue-glass  mounting  for 
sub-stage,  which  is  adapted  to  any  microscope  without  the 
condenser.  A  blue-glass  chimney  for  the  lamp  may  be 
made  to  give  substantially  the  same  results. 


16 


diatoms ;  and  probably  the  most  decisive 
test  will  be  by  resolution  of  the  Pleuro- 
sicjma  angulatum,  with  one-fourth  of  me- 
dium angular  aperture.  Such  an  objective 
will  only  make  the  resolution  "clearly" 
without  the  condenser,  when  the  light  is 
somewhat  oblique.  Moreover,  the  resolu- 
tion is  not  made  instantly,  but,  even  with 
a  fairly  expert  operator,  will  require  a 
little  expenditure  of  time  in  manipulation. 
With  the  condenser,  on  the  contrary,  such 
an  objective  will  resolve  the  test  instantly, 
or,  at  any  rate,  as  nearly  so  as  one  can  rack 
the  condenser  to  its  proper  position  in  the 
sub-stage  ;  and  this,  too,  with  the  smallest 
diaphragm  in  place,  so  that  the  resolution 
is  in  reality  made  with  nearly  central 
light.* 

The  foregoing  are  the  more  important 
tools  to  be  used  in  a  study  of  the  biology 
of  a  water  supply.  For  dissections, 
knives,  needles,  watch-glasses,  tweezers, 
a  dissecting  microscope,  and  other  acces- 
sories, will  be  required. 

*  For  hints  on  the  use  of  the  condenser,  see  "  Manipu- 
lation of  the  Microscope,"83  by  Edward  Bausch. 


17 


COLLECTING    FROM    WATER    MAINS. 

Whoever  undertakes  to  unravel  the 
problem  of  the  biology  of  a  water  supply, 
will  find  it  necessary  to  investigate  in 
many  directions ;  and  a  few  hints  on  the 
subject  of  general  collecting  are  therefore 
included. 

In  the  first  place,  when  it  is  desired  to 
collect  samples  from  the  mains  of  a  public 
water  supply  without  reference  to  the 
method  of  quantitative  enumeration, 
described  in  Part  II.,  the  simple  method 
of  fastening  a  single  thickness  of  fine- 
cotton  cloth  over  an  ordinary  cock,  and 
allowing  the  water  to  flow  freely,  will 
answer  every  purpose.  It  is  necessary  to 
allow  the  water  to  flow  full  size  of  open- 
ing, in  order  that  the  various  suspended 
objects  may  be  carried  along  and  brought 
into  the  filter ;  and  two  hours  of  such  flow 
will  ordinarily  be  sufficient.  For  cleaning 
the  specimens  from  the  filter  it  should, 
after  removal  from  the  cock,  and  after 
turning  wrong  side  out,  be  either  dabbled 
in  a  small  quantity  of  water  contained  in  a 


18 


deep  dish,  or  washed  off  with  an  ordinary 
laboratory  wash  bottle.  In  this  way  the 
filterings  of  a  number  of  hours  may  be 
concentrated  into  an.  amount  of  water  not 
more  than  enough  to  fill  a  medium  sized 
beaker.  After  standing  for  a  short  time, 
samples  may  be  selected,  either  from  the 
sediment  at  the  bottom,  or  from  other  por- 
tions of  the  liquid,  depending  upon  what 
particular  class  of  organism  the  operator 
may  be  looking  for.  Further  details  of 
this  operation,  with  references  to  the  lit- 
erature, are  given  in  Part  II. 

TRANSPARENT    ORGANISMS. 

In  the  examination,  organisms  are 
frequently  encountered  so  nearly  trans- 
parent that  the  eye  fails  to  discern  the 
structure.  In  such  cases  the  examination 
may  be  materially  assisted  by  the  use  of 
some  staining  reagent  which,  added  to  the 
sample,  has  the  effect  of  bringing  out 
the  hidden  structure.  For  such  purpose 
the  various  aniline  dyes  are  useful,  though 
probably  hsernatoxylin  is  most  frequently 
applied.  For  the  infusoria,  a  solution  of 


iodine,  in  iodide  of  potassium,  and  osmic 
acid  have  both  been  successfully  used. 
They  color  the  structure,  leaving  the  cilia 
extended. 

The  use  of  first  quality  objectives,  how- 
ever, by  reason  of  their  superior  defini- 
tion, renders  the  application  of  staining 
reagents  less  necessary  than  with  ordinary 
objectives. 

COLLECTING      FROM     STREAMS     AND     RESER- 
VOIRS. 

Collections  from  streams,  reservoirs, 
lakes,  or  ponds,  used  as  sources  or  parts 
of  public  water  supplies,  will  have  to  be 
made  by  different  methods,  and  the  par- 
ticular one  used  will  depend  upon  what  it 
is  desired  to  collect. 

For  fresh-water  algae,  the  implements 
needed,  in  addition  to  long  rubber-boots, 
are  substantially  as  follows  :  — 

1.  A  small  iron  or  tin  ladle,  two 
inches  across,  and  provided  with  teeth 
for  one-third  of  'the  circumference  oppo- 
site the  handle.  The  handle  is  a  hollow 
ferrule,  and  serves  to  attach  the  ladle  to 


20 


one's  walking-stick.  The  teeth  are  bent 
inward,  in  order  to  catch  masses  of  algae 
beyond  arm's-length. 

2.  A  small  sieve  is  necessary  for  inter- 
cepting floating  masses  of  desmids,  etc. 

3.  A  common  iron  spoon  for  removing 
thin   layers    of    mud   along   the    margins 
where  the  presence  of  desmids  or  diatoms 
is  for  any  reason  suspected. 

4.  An   iron   rake  for  bringing  up  sam- 
ples   from    the    bottom    is    of    value.     It 
should  have  enough  strong  cord  attached 
to  reach  the  bottom  of  the  deepest  body 
of  water  to  be  examined. 

The  foregoing,  with  a  number  of  bottles, 
a  good  pocket  magnifier,  and  a  strong 
jack-knife,  will  be  the  principal  tools  re- 
quired for  collecting  the  fresh-water  algae.* 
Indeed,  the  author's  own  collections  have 
thus  far  been  all  made  with  the  help  of 
a  few  bottles,  a  walking-stick,  a  rake,  and 
for  objects  at  a  distance  on  the  surface, 
such  means  of  reaching  them  as  could  be 
readily  improvised  on  the  ground. 

*  "  Collector's  Handy-Book,"  by  Jphann  Nave.96 


21 


Mr.  Wolle's  outfit  for  collecting  des- 
mids  consists  of  four  or  five  tin  cans  (to- 
mato or  fruit),  one  within  the  other  for 
convenience  of  carriage;  ten  or  a  dozen 
wide-mouthed  bottles,  and  a  ring  net  simi- 
lar to  that  described  below  for  collecting 
the  entomostraca.* 

According  to  the  late  Dr.  Leidy, 
rhizopods  are  best  collected  by  the  use 
of  a  small  tin  ladle,  as  above  described. 
Instead  of  a  walking-stick,  Dr.  Leidy 
carried  on  his  collecting  tours  a  jointed 
pole  of  two  or  three  pieces,  each  about 
five  feet  long.  The  ladle,  or  dipper,  was 
used  by  slowly  skimming  the  edge  along 
the  bottom  of  the  water,  so  as  to  take  up 
only  the  most  superficial  of  the  ooze, 
which  was  then  gently  raised  from  the 
water  and  transferred  to  a  glass  jar.f 

Dr.  Leidy  states  that  he  was  most 
successful  in  finding  rhizopods  in  the  ooze 
near  the  shores  of  lakes  and  ponds,  possibly 
due  to  the  fact  that  the  ooze  near  the 

*  "  Desmids  of  United  States,"  by  Rev.  Francis  Wolle,** 
p.  13. 

t  "  Fresh-Water  Rhizopods  of  North  America,"  t;7  pp. 
7  to  13  inclusive,  are  of  great  interest  to  the  collector. 


22 


shores  could  be  better  seen,  thus  enabling 
the  collector  to  get  the  desired  material. 

The  infusoria  are  the  most  widely  dis- 
tributed of  any  class  of  microscopic  life. 
Infusions  of  every  sort  and  kind,  and 
waters  of  every  degree  of  purity,  contain 
them.*  Even  falling  rain  and  dew  provide 
a  home  for  extensive  series.  Certain 
classes  are  found  only  in  salt  and  brakish 
water,  and  others  in  putrid  infusions. 
These  may  be  excluded  as  beyond  the 
limits  of  the  present  inquiry. 

Weedy  ponds,  or  weedy  nooks  in  reser- 
voirs or  lakes,  and  slowly  running  water, 
are  the  most  favorable  collecting  fields  for 
the  species  we  are  at  present  interested  in. 
In  such  places  one  may  profitably  examine 
finely  divided  living  plants  for  specimens 
of  the  more  sedentary  species,  such  as  the 
Ciliata  Flagellata.  Dead  and  decaying 
leaves  in  the  water  should  be  examined  for 
colonies  of  Vorticella  and  Euglena.  Cer- 
tain of  the  entomostraca,  as,  for  instance, 
Cyclops  and  Canthocamptus,  and  the  higher 

*  Kent's  "  Manual  of  the  Infusoria,"64  ("  The  Distribu 
tion  of  the  Infusoria,")  p.  107,  and  following. 


23 


crustacean  forms,  Assellus  and  Gamarus, 
are  likely  to  be  covered  with  some  of  the 
parasitic  species. 

For  the  collection  of  the  infusoria  one 
needs  most  a  dipping-bottle,  and  some 
means  of  reaching  beyond  arm's-length, 
together  with  several  small  bottles  to 
which  to  transfer  the  collections  from  the 
dipping-bottle. 

A  dipping  bottle,  as  used  by  the  author 
in  his  collecting -trips,  consists  of  an 
ordinary  two-ounce  morphine  bottle,  fast- 
ened to  the  end  of  a  walking-stick  by  a 
strong  rubber  band  around  the  neck  of 
the  bottle,  with  the  end  of  the  stick  pass- 
ing between  the  band  and  the  neck.  For 
concentrating  the  dippings,  a  large-mouthed 
twelve-ounce  bottle  with  two  funnels,  one 
of  them  small  enough,  when  the  stem  is 
thrust  through  a  small  hole  in  the  cork,  to 
pass  down  into  the  body  of  the  bottle  in 
an  inverted  position,  has  been  used.  The 
mouth  of  this  funnel  is  covered  with  a 
piece  of  light  cotton  cloth.  The  other 
funnel,  which  is  larger,  also  has  its  stem 
passing  through  the  cork,  but  in  an  up- 


24 


right  position.  The  dippings  are  poured 
into  the  upright  funnel,  pass  down  through 
the  stem  of  same  into  the  bottle,  where 
the  inverted  cloth-covered  funnel  acts  as  a 
strainer,  allowing  the  water  to  flow  up  out 
of  the  bottle,  but  retaining  whatever  of 
microscopic  life  may  have  been  brought 
up  by  the  dipping.*  This  apparatus  has 
been  found  of  use  on  several  occasions 
where  the  particular  organism  desired  ex- 
isted only  in  small  numbers,  and  sparingly 
distributed  through  a  considerable  volume 
of  water. 

The  rotifera  may  be  collected  by  means 
of  the  collecting-bottle  and  concentrating 
apparatus  just  described.  They  are  likely 
to  be  found  in  all  varieties  of  water,  and  a 
formal  enumeration  of  their  habitats  would 
transcend  the  limits  of  the  present  chapter. 
The .  reader  is  referred  to  Hudson  and 
Gosse's  f  new  work  for  detailed  information 
on  this  point. 

*  For  illustrations  of  this  device  see  "  Practical  Micro- 
scopy," by  Geo.  E.  Davies,  second  edition,  p.  130,  chapter 
on  "  Collection  of  Objects." 

t  "  The  Rotifera,  or  Wheel  Animalcules," eo  by  C.  T. 
Hudson,  assisted  by  P.  H.  Gosse.  Chapter  iv.,  on  the 
"  Haunts  and  Habits  of  the  Rotifera." 


25 


Certain  worms  of  the  class  Annulata  are 
indicative  of  badly  contaminated  sewage 
waters.  Where  it  is  desired  to  collect  and 
preserve  them  for  purposes  of  comparison, 
they  may  be  found  in  any  stream  receiving 
sewage,  and  are  easily  obtained  by  use  of 
a  simple  dipping-bottle. 

For  collecting  the  entomostraca  from 
ponds,  lakes,  and  reservoirs,  the  dipping- 
net  is  indispensable.*  This  is  made  by  an 
iron  ring,  about  one  foot  in  diameter, 
attached  by  a  strong  ferrule  to  a  pole  ten 
to  fifteen  feet  in  length.  The  iron  ring 
has  a  bag  fitted  to  it  (a  flour-sack  answers 
every  purpose),  and  the  pole  should  be 
strong  enough  to  allow  of  lifting  some 
considerable  amount  of  water.  This  net 
may  be  used,  not  only  in  shallow  water 
and  among  weeds,  but  also  for  towing 
behind  a  boat  in  deeper  water.f  It  is 
emptied  by  allowing  it  to  drain  through 

*  "  A  Final  Report  on  the  Crustacea  of  Minnesota,"  by 
C.  L.  Herrick,  &8b,  chapter  iv.,  on  "  Collecting,  Preservation, 
and  Miscellaneous  Notes." 

t  For  illustration  of  modification  of  this  net,  especially 
adapted  for  towing  in  deep  water,  see  "  Practical  Micro- 
scopy," chapter  on  "  Collection  of  Objects,"  above  referred 
to.89 


26 


the  meshes  of  the  cloth,  and  then,  when 
only  a  small  amount  of  water  is  left  in  the 
bottom,  transferring  the  same  to  a  wide- 
mouthed  bottle  by  quickly  inverting  the 
bag. 

The  above  covers  the  principal  methods 
and  appliances  for  collecting.  Other  meth- 
ods will,  no  doubt,  suggest  themselves  as 
one  progresses  in  biological  studies. 

In  concluding  the  subject  of  collecting, 
it  is  desired  to  impress  upon  the  reader  the 
importance  of  keeping  a  full  and  complete 
record  of  everything  relating  to  each  col- 
lection, as,  for  instance,  where  it  was  found, 
and  under  what  general  and  special  condi- 
tions. Information  of  this  kind  will  pos- 
sess great  interest  when  making  a  final 
judgment  of  the  value  of  any  given  sample 
for  sanitary  purposes.  For  such  a  record 
the  author  usually  carries  several  small 
blank  gummed  labels,  such  as  are  used  for 
slides.  These  are  numbered,  and  one  is 
pasted  to  each  bottle ;  the  number  being 
made  to  correspond  with  that  of  the  entry 
in  a  small  memorandum-book,  which  com- 
pletes this  part  of  the  collecting-record. 


27 


These  numbers  can  be  carried  in  a  series 
through  an  entire  season's  work,  and 
further  used  for  the  record  of  the  exam- 
ination in  the  laboratory  or  at  home. 

PRESERVATION    OF    MATERIAL. 

Having  collected  the  material,  it  becomes 
an  exceedingly  important  question  how  to 
best  preserve  it  for  future  reference.  Much 
ingenuity  has  already  been  expended  in 
devising  methods  of  separating  micro- 
scopic material  from  the  various  degrading 
contaminations  gathered  with  the  original 
collections,  and  much  still  remains  to  be 
done. 

Diatoms  and  desmids  are  usually  sepa- 
rated by  methods  depending  essentially 
upon  differences  in  the  specific  gravity  of 
various  objects.  For  detailed  description 
of  such  methods,  and  the  necessary  appa- 
ratus, the  reader  is  referred  to  Nave's  "  Col- 
lector's Handy-Book,"  already  mentioned.* 

The   smaller    species  of   diatoms,  when 

*  Also  to  "  Practical  Microscopy,"  »»  pp.  138, 139-288-290. 
See  also  article  "  Diatomaceae,"  in  fourth  edition  of"  Micro- 
graphic  Dictionary  "  ^  ("  Collection  "),  p.  252. 


28 


living,  may  be  separated  by  placing  the 
material  containing  them  in  a  shallow  dish, 
with  a  little  water,  and  laying  over  them  a 
thin  cloth.  The  tendency  to  move  toward 
the  light,  which  seems  inherent  in  all  these 
minute  organisms,  will  cause  them  to  creep 
through  the  meshes  of  the  cloth,  appearing 
on  the  upper  side,  frequently  in  such  quan- 
tities as  to  be  easily  scraped  off  with  a  thin 
knife,  and  entirely  free  from  the  degrading 
material. 

FILAMENTOUS    ALG^. 

The  filamentous  algae  can  be  cleansed  by 
washing ;  but  when  in  fruit  this  needs  to  be 
done  with  the  greatest  possible  care,  other- 
wise the  operator  is  certain  to  lose  that 
which  he  most  desires  to  retain.  Indeed, 
certain  of  them  are  so  delicate,  when  in 
fruit,  that  the  slightest  disturbance  will 
inevitably  cause  them  to  break  up;  and,  as 
a  measure  of  safety,  it  is  often  best  to 
mount  them  without  any  attempt  at  wash- 
Hig.  This  becomes  especially  importanj; 
when  we  consider  that  it  is  absolutely 
impossible  to  identify  numerous  species 


29 


of  fresh-water  algae  except  when  in  fruit; 
and  as  the  fruiting  season  with  many  spe- 
cies is  very  short,  extending  over  only  a 
few  clays  in  some  cases,  we  are  obliged  to 
accept  one  horn  or  the  other  'of  the 
dilemma,  —  either  to  run  the  chances  of 
losing  that  which  makes  certain  the  iden- 
tification, or  else  to  get  into  our  mounts  a 
little  dirt.  In  many  cases  we  are  obliged 
to  accept  the  dirt  with  algae  as  inevitable, 
and  run  no  chances. 

FRESH-WATER    ALGJE    FLUID. 

Until  a  few  years  ago  no  satisfactory 
medium  for  mounting  the  fresh-water  algae 
was  known  in  this  country,  and  even  now 
there  seems  to  be  a  chance  for  slight 
improvement.  King's  Fresh-Water  Algae 
Fluid  *  has,  however,  the  merit  of  preserv- 
ing many  species  almost  perfectly,  and  all 
species  fairly  well.  Its  chief  fault  is  that 
the  endocrome  in  some  of  the  algae  shrink 
slightly,  and  unfortunately  such  shrinking 
usually  has  the  effect  of  obscuring  just  the 

*  Prepared  by  Rev.  John  D»  King. 


30 


features  one  desires  most  to  see.  On  the 
other  hand,  it  preserves  the  chlorophyl 
perfectly,  so  that  even  after  the  lapse  of 
years  the  green  color  remains  as  distinct 
as  on  the  day  of  collection.  Mr.  King  has 
stated  *  that  desmids  mounted  four  years 
ago  are  still  as  bright  as  when  first  mounted. 
This  is  an  excellent  test  of  the  preservative 
properties  of  this  fluid,  as  the  desmids  are, 
on  the  whole,  the  most  delicate,  so  far  as 
the  chlorophyl  is  concerned,  of  all  the 
fresh-water  algae. 

The  following   is  the   formula  for  this 
fluid :  t  — 


Camphor  water 
Distilled  water 
Glacial  acetic  acid*     •„ 
Crystal  copper  chloride 
Crystal  copper  nitrate 


50.00  grammes. 
50.00  grammes. 

0.50  grammes. 

0.20  grammes. 

0.20  grammes. 


This  should  be  filtered  after  solution. 
The  following  preservative  fluid  is  sim- 

*  Private  communication. 

t  This  is  really  Petit's  formula;  but  it  has  acquired  the 
name  of  King's  Fluid  in  this  country,  from  the  fact  that  it 
was  introduced  by  Mr.  King,  and  first  used  by  him  in  his 
classes. 


31 


ilar  to  Mr.  King's,  and  for  many  species 
works  equally  well :  *  — 

Dissolve  fifteen  grains  of  acetate  of  cop- 
per in  a  mixture  of  four  fluid  ounces  of 
camphor  water  and  four  fluid  ounces  of  dis- 
tilled water,  add  twenty  minims  of  glacial 
acetic  acid  and  eight  fluid  ounces  of 
t  Price's  glycerine,  and  filter. 

This  fluid  is  said  to  answer  well  for  pre- 
serving algse  in  tubes,  and  for  mounting. 

MOUNTING    IN    FLUIDS. 

The  use  of  a  fluid  medium,  however 
well  it  may  preserve  the  distinctive  fea- 
tures of  the  algse,  has  the  serious  disadvan- 
tage that  the  mounts,  if  not  made  with  the 
greatest  care,  are  liable  to  leak,  and  this 
means,  of  course,  the  loss  of  the  prepara- 

*  This  is  Morehouse's  formula  as  given  in  vol.  iv.  of 
The  American  Monthly  Microscopical  Journal.  Mr. 
Morehouse  suggests  varying  the  specific  gravity  by  cluuige 
of  proportion  of  glycerine;  and  systematic  study  in  this 
direction  would  probably  result  in  the  finding  of  a  series 
of  fluids  adapted  to  nearly  all  the  fresh-water  algae. 
Hantzsch's  method,  described  in  Nave's  "Handy-Book," 
is  a  hint  for  such  a  study. 

t  Bower's  glycerine,  which  is  the  standard  article  in 
this  country,  will  answer  equally  well.  It  is  more  truly 
neutral  than  Price's. 


32 


tion.  Mr.  King  has  experimented  with 
cements  to  meet  this  difficulty,  and  his 
Lacquer  Cell  and  Finish  *  is  claimed  to 
furnish  a  tolerably  safe  remedy.  With 
this  cement  thin  cells  are  run  on  slides 
with  a  turn-table ;  and  after  drying,  the 
mounting  may  be  proceeded  with  in  the 
usual  manner. 

Mr.  King's  directions  for  mounting  in 
fluids  are  as  follows  :  f  — 

1.  Allow  the   cell  to  harden  perfectly. 
It  can  be  hardened  with  artificial  heat  in 
a  few  hours. 

2.  Bring   the    cell    to    an    even   surface 
with  a  fine  file,  or  by  warming  and  press- 
ure with  a  smooth,  flat  metallic  or  glass 
surface. 

3.  Ring  the  outer  half  of  the  flattened 
surface  with  King's  White  Cement. 

4.  Lay  on  the  cover  and  press  it  firmly 
to  its  place,  and  be  sure  that  it  adheres  to 
the  cell  at  every  point. 

*  For  sale  by  th«  Bausch  &  Lomb  Optical  Company. 
The  cements  may  also  be  obtained  directly  from  Mr. 
King. 

t  These  directions  are  intended  by  Mr.  King  to  apply 
particularly  to  mounting  in  cells  composed  of  his  Lacquer 
Cell  and  Finish  Cements. 


33 


5.  To  seal  the  cell,  pass  it  two  or  three 
times   slowly  over  the  flame   of   a  spirit- 
lamp  to  soften  it,  then  apply  just  pressure 
enough  to  the  cover  to  imbed  it  slightly  in 
the  cell.     To  do  this  nicely  may  require  a 
little  practice. 

6.  Finish    with   the    same,    or    another 
color,  to  fancy. 

It  is  a  good  plan  to  put  a  ring  of  the 
white  cement  around  the  edge  of  the  cover 
before  applying  the  final  coat  of  lacquer 
finish  ;  or,  if  preferred,  a  good  finish  can  be 
made  with  the  white  cement  alone.* 

King's  Fluid,  diluted  with  one-half 
water,  answers  well  as  a  medium  for 
mounting  the  infusoria. 

GLYCERINE    JELLY. 

Glycerine    jelly   is    also    an    excellent 
medium   for   mounting   many    species    of 
fresh-water  algae.    Indeed,  Dr.  Cooke  f  con- 
siders it,  on  the  whole,  the  best.     The  gly-  • 
cerine  jelly  has  the  advantage  of  making 

*  For  formula  for  King's  cements,  see  Behrens'  "  Guide 
to  the  Microscope  in  Botany,"  ^  p.  235,  236. 

t  "  British  Fresh-Water  Alga,"  by  M.  C.  Cooked 


34 


mounts  safe  from  the  danger  of  leaking, 
but  delicate  filaments  are  badly  distorted. 
It  has  been  used,  however,  for  Nostoc  and 
Ulothrix  with  good  results. 

Mounting  with  glycerine  presents  some 
difficulties  of  technique  ;  and  the  following, 
on  glycerine  jelly  and  its  use  in  mount- 
ing, is  from  Mr.  King,  who  is  an  expert  in 
its  use.  Mr.  King  says  :  *  — 

"  I  put  up  a  jelly  after  Kaiser's  for- 
mula, t  with  the  improvement  of  a  spe- 
cially selected  gelatine  made  from  the 
swimming  bladder  of  the  sturgeon,  that 
requires  less  glycerine,  and  is  less  objec- 
tionable, than  any  other  I  have  ever  used. 
...  It  is  a  splendid  jelly,  and  will  stand 
hot  weather  without  melting. 

"As  to  my  methods  of  using,  I  melt  it 
on  the  slide,  in  the  quantity  needed  to 
nearly  fill  the  cell,  placing  the  object 
where  I  want  it,  and  taking  off  every  air- 
bubble  that  can  be  seen  with  the  naked 
eye ;  after  which  it  is  put  by  and  allowed 
to  harden.  I  then  melt  a  little  of  the 
jelly  on  the  cover  glass,  breathe  hard  on 

*  Private  letter.  t  Behrens',  85  p.  220. 


35 


the  slide,  turn  the  cover  over  quickly  and 
put  it  on  the  object,  being  sure  that  no  air- 
bubbles  are  caught  under  the  cover.  I 
then  put  on  a  delicate  clip,  pass  it  over  a 
spirit-lamp  till  it  warms  enough  to  come 
to  its  bearings ;  let  it  harden ;  clean  off 
the  greatest  part  of  the  jelly  with  a  pine 
stick  sharpened,  after  which  the  slide  is 
put  into  a  dish  of  water  and  washed  off 
clean  with  a  small  bristle-point  brush. 
The  slide  is  then  carefully  wiped  dry 
and  finished."  * 

-In  using  glycerine  jelly,  the  author  has 
found  it  desirable  to  have  the  jelly  one  or 
two  inches  deep,  in  a  five  or  six  inch  test- 
tube.  This  tube  is  stopped  with  a  cork,  in 
which  is  secured  a  glass  rod  about  one- 
eighth  of  an  inch  in  diameter,  drawn  to  a 
blunt  point  at  the  lower  end,  and  of  such 
length  as  to  reach  just  short  of  the  bottom 
of  the  tube.  In  mounting,  the  object  is 
first  placed  in  position  in  the  cell,  and 
having  warmed  the  jelly  in  the  test-tube, 

*  Additional  hints  on  mounting  In  glycerine  jelly  may 
be  found  in  "  Practical  Microscopy,"89  chapter  xiii.,  "  The 
Preparation  and  Mounting  of  Objects,"  and  in  Behrens' 
"  Guide  to  the  Microscope  in  Botany."  85. 


over  the  chimney  of  the  lamp,  which  fur- 
nishes illumination  for  the  microscope, 
the  glass  rod  with  a  drop  of  the  melted 
jelly  upon  it  is  brought  to  the  object.  Air- 
bubbles  are  removed,  and  the  balance  of 
the  operation  proceeded  with  substantially 
as  described  by  Mr.  King.  This  is  found 
less  troublesome  than  the  cutting  of  small 
pieces  of  the  jelly,  as  practised  by  Mr. 
King,  and  the  difficulty  of  getting  rid  of 
the  air-bubbles  from  the  melted  jelly  is  no 
greater.  . 

KILLING    AND    FIXING. 

*  Glycerine  and  glycerine  jelly  are  also 
the  most  useful  mediums  for  mounting  the 
entomostracan  Crustacea.     They  work  ad- 
mirably for  all  the  species  included  in  the 
order  Copepoda,  but  for  the  Cladocera  they 
shrink   the   tissue   unless    it    is   first   sub- 
mitted to  special  treatment ;  namely,  the 
crustacean  should  be  instantaneously  killed 
with  some  reagent,  which,  while  producing 
death,  leaves  the  body  in  all  its  parts  en- 

*  "  Final  Report  on  the  Crustacea  of  Minnesota,"  by  C. 
L.  Herrick.<r'8b 


37 


tirely  unaltered.  For  this  purpose  osmio 
acid  has  been  most  used ;  but  this  is  not 
entirely  successful,  due  to  the  fact  that  it 
discolors  the  tissue. 

Prof.  Herman  Fol  has  discovered  that 
muriate  of  iron  (ferric  perchloride)  pro- 
duces not  only  instantaneous  death,  but  a 
fixation  of  all  the  parts,  with  very  little 
discoloration  or  shrinkage.*  According  to 
Herrick,  the  alcoholic  solution  is  diluted 
to  about  two  per  cent,  and  applied  to  a 
small  quantity  of  water,  in  which  the  ani- 
mal is  swimming.  The  water  is  poured 
off  and  the  crustacean  washed  with  seventy 
per  cent  alcohol,  to  which  a  few  drops  of 
nitric  acid  may  be  added  to  remove  the 
iron  salts. 

Osmic  acid  is  highly  recommended  by 
Kent  t  for  killing  and  fixing  infusoria.  By 
its  use  he  says  they  may  be  preserved  as 
naturally  as  though  living  ;  and  the  matter 
of  securing  permanent  mounts  of  nearly  all 
types  of  infusoria  becomes  merely  a  ques- 

*  C.  L.  Herrick  (loc.  c«.). 

t  "Manual  of  the  Infusoria."64  "  Preservation  of  the 
Infusoria,"  p.  113. 


38 


tion  of  patient  manipulation.  Coloring  re- 
agents may  also  be  used  in  connection  with 
the  osmic  acid,  so  that  all  the  structures, 
such  as  Cilia  and  Flagella,  the  internal 
endoplast,  and  in  Euglena  the  colors  also 
are  preserved;  "the  animalcules,  excepting 
for  the  absence  of  motion,  being  scarcely 
distinguishable  from  the  living  organisms." 

For  killing  and  fixing  hydra,  Huxley 
and  Martin  *  recommend  first  placing  the 
animal  in  a  small  quantity  of  water,  and 
after  the  hydra  has  extended  its  tentacles, 
adding  boiling  water. 

The  author  has  used  for  this  purpose  the 
muriate  of  iron,  as  recommended  by  Fol, 
for  the  Crustacea,  and  was  successful  in 
killing  the  hydra  in  an  extended  condition ; 
but  the  structure  soon  broke  down,  so 
that,  from  present  information,  it  appears 
that  the  muriate  of  iron  cannot  be  used 
where  permanent  preparations  of  hydra 
are  desired. 

The  rotifera  may  be  mounted  in  glycer- 
ine jelly,  and  for  killing  and  fixing,  both 

*  "  Practical  Biology,"  101  by  T.  H.  Huxley,  assisted  by 
H.  N.  Martin ;  chapter,  "  The  Fresh-Water  Polypes,"  p.  104. 


39 


osmic  acid  and  muriate  of  iron  have  been 
-found  to  work  well. 

The  foregoing  includes  a  few  of  the 
elementary  facts.  Whoever  wishes  to  pur- 
sue the  subject  extensively,  may  find 
abundant  references  to  literature  in  the 
list  following  Part  II. 


PART  II. —  QUANTITATIVE., 

The  Microscopical  Examination  of 
Potable  Water. 


LIMITATION    OF    THE    SUBJECT. 

IN  a  paper  on  "  Recent  Progress  in  Bio- 
logical Water  Analysis/7  21a  by  Prof.  Wm. 
T.  Sedgwick,  of  the  Massachusetts  Insti- 
tute of  Technology,  is  found  a  clear  defi- 
nition of  the  classes  of  micro-organisms  as 
occurring  in  potable  waters.  The  defini- 
tion there  given  has  been  again  used  by 
Prof.  Sedgwick,  in  a  "  Report  on  the  Bio- 
logical Work  of  the  Lawrence  Experiment 
Station,"  21d  as  published  in  1890  ;  and  it 
may  be  taken  as  representing  the  latest 
views,  both  in  this  country  and  abroad,  in 
relation  to  the  classification  of  this  sub- 
ject. 

40 


41 


Tabulated,    it    assumes    the    following 
form  :  — 

(1.  —  MICROSCOPICAL,  OR- 
GANISMS. 

a.  Not  requiring  spe- 
cial cultures. 

6.  Easily  studied  with 
the  microscope. 

c.  Microscopic  in   size, 

or  slightly  larger. 

d.  Plants  or  animals. 


MICRO-ORGANISMS. 

Plants  or  animals, 
either  in  visible  or  barely 
visible  to  the  naked 
eye. 


2.  —  BACTERIAL  ORGAN- 
ISMS. 

a.  Requiring        special 

cultures. 

b.  Difficultly       studied 

with  the  microscope. 

c.  Microscopic   or  sub- 

microscopic  in  size. 
\  .d.  Plants. 

The  present  monograph  will  deal  exclu- 
sively with  the  microscopical  organisms, 
without  reference  to  the  bacterial  organ- 
isms. The  latter  have  been  treated  so 
extensively  in  the  last  few  years  as  to 
greatly  obscure  the  former,  with  the  result 
of  entirely  neglecting  a  promising  branch 
of  water  analysis.  At  the  present  time  it 
is  proposed  to  give  a  brief  history  of,  and 
describe  a  new  method  of  quantitatively 
determining,  the  microscopical  organisms. 


42 


The  sanitary  significance  and  relative 
economic  importance  of  the  microscopical 
forms  will  be  treated  in  another  volume. 

COMPLETE    SANITARY    ANALYSIS. 

By  way  of  illustrating  the  importance  of 
a  quantitative  determination  of  the  micro- 
scopical organisms,  we  will  briefly  discuss 
the  requirements  of  a  complete  study  of 
potable  water  from  the  sanitary  point  of 
view. 

In  the  first  place,  it  has  been  proven 
many  times  that  a  single  analysis,  whether 
chemical  or  biological,  is  entirely  without 
significance  in  determining  the  sanitary 
value  of  ordinary  potable  waters.  The 
evidence  grows  stronger  from  day  to  day, 
that  in  selecting  sources  of  supply  for 
towns,  public  institutions,  large  manufac- 
turing establishments,  or  any  other  place 
where  an  error  in  judgment  would  involve 
the  health  of  a  number  of  human  beings, 
complete  studies  from  every  possible  point 
of  view  should  be  made.  If  the  case  in 
hand  is  important  enough  to  justify  the 
expense  (and  it  always  will  be  in  the  case 


43 


of  large  town  supplies),  the  examinations 
should  extend  over  a  whole  season,  and 
-in  difficult  cases  over  two  or  more  sea- 
sons. This  conclusion  is  the  plain  teach- 
ing of  experience,  as  exhibited  in  the 
water  supplies  of  most  of  the  cities  of  this. 
country. 

Assuming  that  a  given  source  is  either 
from  a  deep  pond  or  lake,  or  from  a  creek 
or  river,  or  involves  the  impounding  of 
large  bodies  of  water  in  storage  basins,  it 
is  premised  that  the  authorities  in  charge 
thereof  should  be  possessed  of  definite 
information  as  to  a  number  of  points  in 
relation  to  what  may  be  termed  the  natural 
history  of  the  water  in  question.  In  order 
to  determine  the  said  points,  four  distinct 
lines  of  investigation  may  be  carried  out,, 
as  exhibited  in  the  following :  — 

1.  —  A    STUDY    OF    THE    ENVIRONMENT. 

Including  detailed  statement  of  topo 
graphical  and  geological  conditions  of 
drainage  area,  together  with  observations 
on  extent  and  character  of  population  and 
industries  of  the  region  as  special  sources 


44 


of  pollution,  with  study  of  normal  samples 
by  (2),  (3),  and  (4). 

2.  —  PHYSICAL    PROPERTIES. 

This  will  include  a  systematic  study, 
with  tabulation  of  results,  including  a 
statement  of  the  following  :  — 

a.  Depth  from  which  samples  are  taken. 

b.  Temperature. 

c.  Specific   Gravity  for  actual  depth  and 

temperature. 

d.  Color. 

e.  Turbidity. 

f.  Sediment. 

g.  Taste  and  odor. 


3.  —  CHEMICAL    ANALYSIS 

a.  Albuminoid  Ammonia,  j  J  | 

b.  Free  Ammonia. 

c.  Nitrites. 

d.  Nitrates. 

e.  Chlorine. 

f.  Hardness. 

g.  Total  Solids. 

h.  Loss  on  Ignition. 


45 

4. —  BIOLOGICAL    EXAMINATION. 

(4a.)  PLANTS. 

1.  Chlorophycese. 

2.  Cyanophycese. 

3.  Diatomaceae. 

4.  Fungi,  including  Bacteria. 

(46.)    ANIMALS. 

1.  Crustacea. 

2.  Vermes  (Rotifera  etc.). 

3.  Polyzoa. 

4.  Infusoria. 

5.  Rhizopods. 

6.  Spongidse. 

7.  Miscellaneous. 

(4c.)  AMORPHOUS    ORGANIC    MATTER. 

The  microscopical  examination  will  in- 
clude the  determination  of  everything 
under  (4),  except  the  bacteria.  It  is  thus 
seen  to  occupy  an  important  place  in  a 
scheme  for  a  complete  sanitary  analysis ; 
and  having  remarked  that  a  large  number 
of  examinations  made  during  the  last  three 
years  by  (1)  the  biologists  of  the  Massa- 
chusetts State  Board  of  Health,  (2)  the 


46 


biologists  of  the  Connecticut  State  Board 
of  Health,  and  (3)  by  the  present  writer, 
have  put  the  matter  on  a  fair  working 
basis,  we  may  proceed  to  describe  the 
present  state  of  the  art  of  making  such 
examinations :  — 

HISTORICAL. 

The  first  systematic  examination  of  a 
water  supply  ever  made  was  by  Dr^  JHa§&all 
of  the  water  supply  of  London,  in,.4£3Q.7 
The  results  were  given  in  an  illustrated 
memoir,  and  stand  unique,  as  furnishing  a 
beginning  for  scientific  study  of  this  im- 
portant and  interesting  subject. 

In  1865  L.EadJijQfer 19  published  an 
account  of  an  examination  of  well  waters 
in  Munich. 

In  1&70  Prof.  jCqhn,  of  Breslau,  pub- 
lished a  paper  on  the  Microscopical  Analy- 
sis of  Well  Waters,  and  indicated  clearly 
therein  the  significance  of  such  studies. 3* 
In  this  paper  Prof.  Cohn  made  the  fol- 
lowing generalizations,  which  are  inter- 
esting as  showing  the  advanced  views  to 
which  he  had  arrived  :  — 


47 


1.  Diatoms   and   green  algae,   Conferva, 
Protococcus,  Scenedesmus,  etc.,   indicate   a 
water  to  which  light  lias  had  access,  and 
one  poor  in  organic  matter. 

2.  Certain  of  the  larger  infusoria,  espe- 
cially the  ciliated  forms,  Nassula,  Loxodea7 
Urastyla,  etc.,  feed  on  these  algae  ;  while 
upon   both    the    infusoria    and   the    algae 
feed  — 

3.  Entomostracans,  —  Daphnia,  Cyclops, 
Cypris,  —  worms,  such  as  naids  and  rotif era 
and  insect  larvae. 

Prof.  Dr.  L.  Hirt,  also  of  Breslau,  pub- 
lished a  paper  upon  the  Principles  and 
Methods  of  the  Microscopical  Investiga- 
tion of  Waters,  in  1879.8 

Dr.  F.  Hulwa  published,  iiL-1885,8*  a, 
paper  giving  tabulated  results  obtained  by 
the  methods  described  by  Hirt. 

The  first  edition  of  Maotkuiald's  "  Guide1 
to  the  Microscopical  Examination  of 
Drinking  Water,"  H  appeared  in  1,§T£L  The; 
second  edition  (1883)  contains  a  method  of 
examination  which  will  be  referred  to 
hereafter. 

In  1884   Dr.  H.  C.    Sorby  published  a 


48 


paper  on  the  Detection  of  Sewage  Con- 
tamination by  the  Use  of  the  Microscope, 
arid  on  the  Purifying  Action  of  Minute 
Animals  and  Plants.23 

In  FphrnaTvJjggfl,  Mr.  A_.  L.  Kca.n  9  pub- 
lished, in  Science,  a  method  of  making  the 
quantitative  examination  of  the  micro- 
scopical plants  and  animals  in  potable 
water. 

In  Septembej^jLSSO^  Prof^ JYmiam_  T. 
Sedgwick  published,  in  the  paper  on  Recent 
Progress  in  Biological  Water  Analysis 
already  referred  to, 21a  what  is  known  as 
the  sand  method  of  making  these  exami- 
nations. 

In  September.  1890,  the  present  writer 
published  a  paper  on  the  Biological  Exami- 
nation of  Potable  Water.200 

About  Jan.  1,  1891^  the  Special  Eeports 
of  the  MassacTmsetts  State  Board  of 
Health  appeared.130  Part  I.,  Examination 
of  Water  Supplies,  contains  a  method  of 
making  the  quantitative  examination  as 
devised  by  Mr.  G-.  H.  Parker,  formerly 
biologist  to  that  Board.13c  Part  II.,  Puri- 
fication of  Sewage  and  Water,  contains  an 


49 


account  of  the  various  methods,  and  an 
abstract  of  the  literature  to  the  date  of 
publication.130 

The  foregoing  are  the  more  important 
sources  of  information  to  be  consulted  by 
one  desiring  to  pursue  the  general  subject 
of  the  microscopical  examination  of  water 
historically.  The  titles  of  a  few  other 
papers  and  references  of  less  importance 
may  be  given. 

Mr.  C.  M.  Vorce  published  papers  on 
Forms  observed  in  Water  Of  Lake  Erie,25  in 
1881  and  1882.  These  papers  contain 
some  useful  generalizations  as  to  persist- 
ency of  certain  forms  in  large  bodies  of 
water  at  all  seasons  of  the  year. 

Mr.  Henry  Mills  published  a  paper  on 
the  Micro-Organisms,  in  the  Buffalo,  N. 
Y.  Water  Supply,  in  1882. 15  This  paper 
contains  an  estimate,  based  on  actual  obser- 
vation, of  the  amount  of  microscopic  life  in 
the  Niagara  Eiver. 

Dr.  C.  A.  Chamberlain  published  a  paper 
on  Organic  Impurities  in  Drinking  Water, 
in  1883.3 

Dr.  Arthur  J.  Wolff  published  a  paper 


50 


on  the  Sanitary  Examination  of  Drinking 
Water,  in  1886.28 

The  present  writer  published  a  paper  on 
the  Micro-Organisms  in  Hemlock  Water,  in 
1888.20a 

In  1889  Tiemann  and  Gartner's  Chemi- 
cal, Microscopical,  and  Bacteriological  In- 
vestigation of  Waters  24  appeared.  In  it 
may  be  found  an  abstract  of  the  useful  for- 
eign literature  of  the  subject,  and  many 
hints  of  value  in  interpreting  results. 

THE    METHOD    OF    DR.    HASSALL.7 

Dr.  Hassall,  although  the  first  to  apply 
the  microscrope  to  the  determination  of  the 
organic  constituents  of  water,  has  not  in 
any  of  his  papers  made  it  clear  just  how 
he  obtained  his  results ;  though  we  may 
infer  from  what  he  has  said,  that  his  pro- 
cess was,  essentially,  to  examine  a  drop  of 
the  sediment  contained  in  the  bottom  of  a 
test-tube,  in  which  a  sample  of  the  water 
had  been  allowed  to  stand  long  enough  for 
thorough  sedimentation  to  occur. 


51 


METHODS    OF    THE    GERMAN    BIOLOGISTS. 

Radlkofer 19   leaves  us   entirely   in   the 
dark  as  to  the  methods  used  in  his  examin- 
ation of  the  well-waters  of  Munich ;    but    <^/ 
we  may  infer  that  his  method,  like  that  of 
Cohn  in  the  examination  of  the  waters  of     ^ 
Breslau,  consisted  in  a  direct  microscopical    JK 
study  of  either  a  few  drops  of  water  or  of 
the  sediment. 

Hirt,  in  his  paper,  recommends  the  fol- 
lowing course  of  procedure  : 8  — 

1.  The  direct  observation  of  fresh  sam- 
ples of  the  water,  a  drop  at  a  time ;   as    \ 
many  as  twenty  or  thirty  drops  being  suc- 
cessively scrutinized. 

2.  An     examination     of    the    sediment     ^ 
obtained  after  standing  at  least  two  days. 

3.  A    study    of    the    surface    pellicle, 
should    any   form    after    the    sample    has 
stood  for  a  few  days.* 

In  this  way  Hirt  finds   it  necessary  to 
make  as  many  as  thirty  to  forty  examina- 

*  This  third  course  of  procedure  was  used  previous  to 
the  introduction  of  the  modern  methods  of  bacteriology, 
and  was,  until  about  1881,  the  approved  method  of  studying 
the  bacteria  in  their  relation  to  potable  waters. 


52 


tions  before  completing  the  study  of  any 
given  sample. 

THE    METHOD    OF    DR.    MACDONALD.14 

For  this  method  of  examination  tall, 
-cylindrical  glass  vessels  with  small  rounded 
bottoms  are  recommended.  In  the  absence 
of  the  special  vessels  a  litre  or  half-litre 
measuring-glass  may  be  used.  For  the 
examination  of  a  sample,  one  of  the  tall 
glass  vessels  is  first  filled  with  water, 
after  which  a  circular  disk  of  glass,  resting 
on  a  horizontal  loop  at  the  end  of  a  long 
aluminium  wire  is  lowered  to  the  bottom. 
The  tall  glass  is  covered  and  set  aside  for 
twenty-four  or  forty -eight  hours,  as  the  case 
may  be.  After  standing  the  specified  time 
the  water  is  siphoned  off  with  tubing, 
leaving  only  a  thin  stratum  over  the  disk, 
which  is  then  raised  and  laid  upon  blot- 
ting-paper  to  remove  surplus  moisture. 
The  disk  is  then  covered  with  a  large  cover 
glass,  and  transferred  at  once  to  the  stage 
of  the  microscope  for  direct  examination- 

Dr.  MacDonald  further  says,  an  ordinary 
'watch-glass  may  in  some  cases  be  substi- 


53 


tuted  for  the  disk,  with  advantage,  as  being 
less  likely  to  permit  the  loss  of  sediment 
by  overflow.  Another  plan  suggested  is 
to  siphon  off  the  water  until  only  enough 
remains  to  just  permit  the  sediment  to  be 
shaken  up  with  it,  and  turned  into  a  coni- 
cal-shaped glass,  from  which,  after  standing 
for  a  short  time,  portions  may  be  taken  for 
-examination.  By  proceeding  as  outlined  in 
the  foregoing,  a  judgment  could  be  formed 
as  to  the  amount  and  kind  of  the  organic 
impurity  present.  Independent,  however 
of  the  impossibility  of  establishing  numeri- 
cal relations,  the  practical  difficulties  of 
examinations  on  either  the  plain  glass 
disk  or  in  the  curving  watch-glass  are  con- 
siderable. The  chief  sources  of  possible 
error  in  final  judgment  may  be  enumerated 
as  follows :  — 

1.  During    the    time    of    standing    for 
purpose  of  sedimentation,  a  diminution  of 
the  number  and  kind  of  species    originally 
present  may  be  expected  to  take  place,  by 
reason  of  one  form  eating  another  up. 

2.  Impossibility  of  knowing  that  at  the 


54 

end  of  the  time  allowed  for  sedimentation, 
all  the  forms  originally  present  in  the 
sample  have  fallen  to  the  bottom,  and  are 
present  in' the  sediment. 

3.  In  using  the   plain   glass   disk,  the 
liability  of  losing  some  of  the  sediment 
when  placing  the  cover-glass. 

4.  In   using  the  watch-glass,  difficulty 
of  fully  examining  the  sediment,  on  account 
of  the  curved  bottom. 

5.  In  taking  drops  of  sediment  with  a 
pipette  for  examination  on  a  slide ;  uncer- 
tainty as  to  whether  samples  containing  all 
the    forms   present    in   the  sediment    are 
obtained. 

Dr.  MacDonald's  work  must,  neverthe- 
less, be  considered  of  the  greatest  possible 
value.  His  general  definition  of  technique 
is  good,  especially  the  directions  in  refer- 
ence to  collection  of  samples,  and  methods 
of  insuring  microscopical  cleanliness  at 
every  stage  of  the  operation.  His  book 
should  be  in  the  hands  of  every  person 
using  the  microscopical  method. 


55 


THE    METHOD    OF    DR.    H.   C.    SORBY.  d 

111  1884  Dr.  H.  C.  Sorby,  of  England, 
/iade  a  study  of  different  samples  of  river 
IJid  sea  water,  with  the  object  of  ascertain 
jng  the  number  per  gallon  of  the  various 
small  animals  large  enough  to  be  held  back 
by  a  sieve  with  meshes  about  one  two-hun- 
dredths  of  an  inch  in  diameter.  Amounts 
of  water  varying  from  ten  gallons  down- 
wards, according  to  the  number  of  forms 
present,  were  passed  through  such  a  sieve. 
The  retained  organisms  were  subsequently 
washed  off  into  a  dish,  and  an  enumera- 
tion made,  —  just  how,  Dr.  Sorby  does  not 
state.  The  forms  which  he  was  studying 
were  comparatively  large  (Cyclops  and 
other  Entomostracan  Crustacea)  ;  and  an 
enumeration  could  be  easily  made,  either 
in  a  watch-glass  with  a  low-power  object- 
ive of  considerable  penetrating  power,  or 
in  a  large  flat  cell  of  special  construction, 
by  the  use  of  an  ordinary  hand  magnifier. 
Dr.  Sorby  gives  numbers  per  gallon  of  the 
various  forms  found  in  different  waters ; 
and  we  may  conclude  from  what  he  has  said. 


that  so  far  as  the  larger  microscopical 
forms  are  concerned,  he  considered  that  a 
fairly  accurate  method  of  enumeration  had 
been  used.  He  also  enumerated  the  infu- 
soria, and  states,  that  at  low  water  in  the 
Medway,  above  Chatham,  in  the  first  half 
of  June,  the  average  number  per  gallon  has 
been  about  7.000,  but  sometimes  as  many 
as  16,000.  The  average  size  of  the  infu- 
soria so  enumerated,  he  states  at  one  one- 
thousandth  of  an  inch.  Clearly  a  much 
smaller  mesh  than  was  used  for  the  ento- 
mostraca,  and  special  methods  of  gathering 
would  be  required ;  but  just  how  all  this 
was  accomplished  Dr.  Sorby  has  failed  to 
tell  us.  The  paper  is,  however,  suggestive 
as  to  possibilities  of  future  results,  and 
may  be  profitably  consulted  by  the  student 
of  the  advanced  methods. 

METHODS    USED    IN    THE    UNITED    STATES 
PRIOR   TO    1889. 

Of  the  several  papers  which  have  ap- 
peared in  this  country  previous  to  1889,  it 
may  be  said,  in  a  general  way,  that  the 
authors  of  all  have  apparently  gone  no 


57 


further  towards  a  quantitative  determina- 
tion of  the  microscopical  organisms  than 
to  examine  a  sediment  usually  obtained  by 
allowing  the  water  to  flow  through  a 
strong  cotton  cloth.  When  public  water 
supplies  were  the  subject  of  examination, 
a  bag  of  such  material  was  attached  to  an 
ordinary  laboratory,  or  domestic  cock,  and 
the  water  simply  allowed  to  run,  until,  as 
a  matter  of  judgment,  enough  had  been 
filtered  through  the  cloth  to  insure  a  pro- 
lific sediment.  The  flow  being  stopped, 
the  bag  was  removed,  and,  after  the  water 
still  contained  in  it  had  drained  through, 
the  bag  was  turned  wrong  side  out,  and  the 
organisms  removed  by  dabbling  and  lightly 
washing  in  a  small  amount  of  water  from 
the  supply  under  examination,  contained 
in  a  clean  shallow  dish.  After  so  re^aov- 
ing  the  organisms'  from  the  cloth?  the 
water  containing  them  was  turned  into  a 
conical-shaped  glass,  from  which,  after 
subsidence  of  the  organisms  to  the  bottom, 
samples  were  taken  by  the  use  of  a  pipette 
for  examination  in  the  usual  manner  on  a 
slide.  In  this  way  the  results,  as  detailed 


58 


by  Mr.  Vorce,25  Mr.  Mills,15  and  by  the 
members  of  the  Microscopical  Section  of 
the  Rochester  Academy  of  Science,  as  de- 
tailed in  the  paper  published  by  the  pres- 
ent writer  20a  in  1888,  were  obtained. 

THE    METHOD    OF    MR.  G.  H.    PARKER.13c 

In  1888  Mr.  Parker,  as  Biologist  to  the 
Massachusetts  Board,  worked  out  and  ap- 
plied a  method  for  examination  somewhat 
different  from  any  of  the  preceding.  A 
small  piece  of  cloth  is  taken,  and  firmly 
tied  to  the  stem  of  a  common  glass  funnel, 
in  such  manner  that  the  sample  "of  water 
when  poured  into  the  funnel  would  filter 
through  only  that  portion  of  the  cloth  di- 
rectly in  front  of  the  end.  All  being 
arranged,  two  hundred  cubic  centimetres 
of  tRe  water  to  be  examined  are  poured 
into  the  funnel.  At  the  end  of  the  filtra- 
tion, the  organisms  contained  in  the  water 
are  found  collected  on  the  cloth  on  a  small 
area  of  the  size  of  the  bore  of  the  stem  of 
the  funnel.  The  cloth  is  now  removed; 
and  inverted  over  a  glass  tube  of  some- 
what greater  area  than  the  circular  spot 


of  arrested  organisms.  The  tube  is  so 
held  that  the  end  with  the  inverted  cloth 
is  just  above  the  middle  of  an  ordinary 
glass  slide  ;  and  a  sharp  blast  of  air 
through  the  tube  dislodges  the  sediment 
with  a  small  amount  of  water  upon  the 
slide,  where,  after  covering  with  a  cover 
glass,  it  may  be  examined  under  the  mi- 
croscope. Mr.  Parker  states,  that  this 
method  gives  good  results,  so  far  as  de- 
termining the  kind  of  organisms  is  con-- 
cerned ;  but,  from  a  quantitative  stand- 
point, it  yields  only  rough  approximations. 
The  principal  sources  of  inexactness 
are  :  — 

1.  A  few  of  the  smaller  organisms  pass 
through  the  cloth. 

2.  Impossibility  of    removing    all    the 
organisms  from  the  cloth  to  the  slide. 

3.  Difficulty  of   distributing   the    sedi- 
ment on  the  slide  equally  enough  to  per- 
mit accurate  estimates  of  the  number  of 
the  organisms. 

The  method  of  Mr.  Parker  has  been 
known  as  the  *•'  cloth  method/7  and  is  so 
referred  to  in  the  Massachusetts  reports.130 


THE    METHOD    OF    MR.    A.    L.    KEAN.9 

In  this  method  a  known  quantity  of 
water  (Mr.  Kean  says  100  cubic  centi- 
metres is  a  convenient  unit)  is  put  into  a 
funnel,  in  the  tube  of  which  is  half  an 
inch  in  depth  of  coarse  sand  (24  to  30 
grains  to  the  inch).  The  sand  is  held  in 
place  by  a  plug  of  wire  gauze  in  the  foot 
of  the  funnel,  which,  while  allowing  the 
water  to  pass,  still  holds  the  sand  back. 
After  all  the  water  has  passed  through,  the 
plug  is  removed,  and  one  cubic  centimetre 
of  distilled  or  freshly  filtered  water  thrown 
into  the  stem  of  the  funnel,  by  means  of  a 
pipette.  This  washes  the  sand  and  con- 
tained organisms  down  into  a  watch-glass, 
placed  to  receive  it.  The  grains  of  sand 
sink  to  the  bottom,  leaving  the  organisms 
mostly  suspended  in  the  water.  Stirring 
produces  more  even  distribution,  and  lib- 
erates any  caught  between  the  grains  of 
sand.  A  cell  of  one  cubic  millimetre  vol- 
ume is  provided,  and  to  it  a  portion  of  the 
water  from  above  the  sand  in  the  watch- 
glass,  sufficient  to  just  fill  it,  is  transferred 


61 


for  examination.  The  organisms  contained 
in  the  cell  are  then  counted,  and  from  the 
result  the  total  number  in  the  original 
sample  computed. 

This  method  was  described  by  Mr.  Kean 
in  his  original  communication  9  in  consid- 
erable detail ;  and  to  him,  therefore,  per- 
tains the  credit  of  having  first  published 
a  quantitative  method  of  determining  the 
microscopical  organisms  in  water.  Credit 
for  first  using  such  a  method  seems  to  per- 
tain to  Dr.  H.  C.  Sorby,  though  with  what 
measure  cannot  be  determined  in  the  ab- 
sence of  the  detail. 

The  chief  defect  of  Mr.  Kean's  method 
is  in  the  smallness  of  the  amount  actually 
examined,  a  difficulty  which  limits  the 
accuracy  of  the  method  in  four  ways :  — 

1.  The  amount  of  one  cubic  millimetre 
is  so  small  that  important  forms  are  easily 
overlooked. 

2.  The  cubic  millimetre  is  only  the  one 
one-thousandth   part  of    the  cubic    centi- 
metre, and  the  necessity  of  multiplying  by 
1,000  leads,  with  an  error  of   one  in   the 
count  to  an  error  of  1,000  in  the  result,  as 


62 


applying  to  the  one  cubic  centimetre  in  the 
Watch-glass.  With  an  original  quantity 
of  100  cubic  centimetres,  this  again  leads 
to  an  error  of  10,  per  cubic  centimetre,  in 
the  final  result. 

3.  If  only  one  of  a  given  form  appears 
in  the  count,  it  must  be  interpreted  as  in- 
dicating 1,000  in  the  one  cubic  centimetre 
in  the  watch-glass,  whereas  it  may  possi- 
bly have  been  the  only  one  there. 

4.  The  impossibility  of  getting  in  the 
reductions  a  number  between  0  and  10  per 
cubic   centimetre.     To  get  one  per  cubic 
centimetre  would  require  the  filtering  of 
1,000  cubic  centimetres  (one  litre)  in  every 
case. 

THE    SAND    METHOD    OF    PROFESSOR 
SEDGWICK.21a' 13c 

The  various  practical  objections  to  the 
method  of  Mr.  Kean  having  been  de- 
veloped by  comparison  and  experiment, 
Prof.  Sedgwick,  in  the  spring  of  1889, 
worked  out  what  is  known  as  the  sand 
method.  In  this,  the  controlling  idea  was 
to  provide  a  remedy  for  the  excessively  - 


63 


high  results  attained  by  the  method  of 
Mr.  Kean.  The  filtration  is  made  as  iix 
Mr.  Kean's  method,  100  cubic  centimetres 
being  likewise  the  quantity  of  water  oper- 
ated upon.  A  cell  50  millimetres  in 
length,  20  millimetres  in  width,  and  about 
2.5  millimetres  in  depth  is  provided.  This 
cell  is  formed  by  cementing  a  brass  border 
upon  an  ordinary  three  by  one  glass  slide. 
Before  setting  this  brass  border,  the  upper 
surface  of  the  slide  is  ruled  into  1,000 
squares,  each  one  millimetre  in  area.  The 
filtration  being  completed,  the  sand,  to- 
gether with  the  organisms,  is  washed  by  a 
small  stream  from  a  wash-bottle  contain- 
ing distilled  water,  into  the  cell  just  de- 
scribed, where  they  are  evenly  distributed 
over  the  bottom  by  the  use  of  a  needle  or 
fine  wire.  We  now  have  •  the  organisms 
from  100  cubic  centimetres  of  water  evenly 
distributed  in  a  cell  of  1,000  square  mil- 
limetres area ;  and  theoretically  it  would 
be  possible,  by  using  a  low-power  object- 
ive, and  taking  in  order  each  square 
millimetre  of  the  area,  to  actually  count 
all  the  organisms  in  the-  cell ;  that  is  to 


64 


Say,  to  count  all  the  organisms  in  the  one 
hundred  cubic  centimetres  of  water  oper- 
ated upon.  In  practice,  however,  the 
counting  of  1,000  squares  would  consume 
so  much  time  as  to  make  the  labor  of  the 
counts  a  serious  burden.  Moreover,  it 
was  found  by  experience  that  a  count  of 
twenty  representative  squares  gave  a  fairly 
accurate  average  of  the  whole  ;  and  twenty 
squares  was  accordingly  adapted  as  the 
unit  count.  In  this  way  50  is  obtained  as 
a  factor  of  multiplication,  instead  of  1,000, 
as  in  the  method  of  Mr.  Kean.  By  count- 
ing a  larger  number  of  squares  a  still 
smaller  factor  results ;  thus  fifty  squares 
counted  gives  a  factor  of  multiplication  of 
only  20. 

For  further  details  of  this  interesting 
and  valuable  advance  in  methods  of  making 
the  microscopical  examination  of  water, 
the  reader  is  referred  to  either  Prof. 
Sedgwick's  original  paper,21a  or  to  his 
further  discussion  of  it  in  the  Massachu- 
setts Board's  Special  Report.130 


65 


THE    PERFECTED    SEDGWICK-KAFTER 
METHOD. 

In  June,  1889,  the  present  writer  organ- 
ized, at  the  instance  of  Desmond  Fitz- 
Gerald,  C.  E.,  Resident  Engineer  of  the 
Western  Division  of  the  Boston  Water 
Works,  a  series  of  investigations  of  the  Bos- 
ton Water  Supply.  Considerable  trouble 
has  occurred  at  various  times  in  this  water 
supply,  by  reason  of  excessive  growths,  at 
irregular  periods,  of  microscopical  organ- 
isms ;  and  the  Boston  Water  Board  deemed 
it  desirable  to  study  the  matter  broadly 
enough  to  presumably  make  some  definite 
addition  to  existing  knowledge  of  the 
laws  governing  such  growths.  A  small 
laboratory  was  erected,  the  necessary  ap- 
pliances secured,  and  arrangements  made 
for  a  systematic  study  extending,  possibly, 
over  a  number  of  years'.  In  July,  Prof. 
Sedgwick  kindly  demonstrated  his  sand 
method  to  Mr.  FitzGerald  and  the  author  in 
his  laboratory,  and  finished  one  of  his  count- 
ing plates.  The  author's  previous  studies 
had  made  him  familiar  with  the  method 


of  Dr.  Mac  Don  aid  and  the  faw  American 
workers,  and  he  was  .able  to  appreciate  the 
advanced  ground  reached  by  Prof.  Sedg- 
wick.  His  sand  method,  while  far  in  ad- 
vance of  that  of  any  other  worker,  seemed, 
however,  somewhat  unsatisfactory  in  this, 
that  the  sand  and  organisms  are  both 
allowed  to  pass  into  the  cell  together;  and 
inasmuch  as  the  finest  grains  of  sand  are 
much  larger  than  many  of  the  organisms, 
it  follows  that  the  enumeration,  however 
carefully  made,  is  only  an  approximation 
to  the  number  actually  present,  and  usually 
falls  short  of 'the  number  present. 

In  the  method  as  now  used  by  the 
author,  the  sand  is  supported  upon  a 
plug  of  wire  cloth,  placed  at  the  lower 
end  of  the  funnel  stem.  After  placing  the 
plug,  the  sand  is  run  into  the  funnel, 
lightly  pressed  to  place  with  a  glass  rod, 
and  from  20  to  40  cubic  centimetres  of 
freshly  filtered  water  allowed  to  run 
through,  in  order  to  insure  thorough  set- 
tling of  the  sand  before  actually  begin- 
ning the  nitration.  The  amount  of  water 
to  be  filtered  is  gauged  by  the  number  of 


67 


organisms  which  it  contains,  as  ascertained 
by    preliminary    inspection.       Generally, 


5? 
P 


however,  as  large  a  quantity  should  be 
used  as  can  be  conveniently  filtered  with- 
out clogging  the  sand  so  much  as  to  render 
the  completion  of  the  process  too  pro- 


68 


longed  ;  and  for  ordinary  samples  500  cubic 
centimetres  has  been  fixed  upon  as  the 
proper  amount.  In  the  -case  of  very  pure 
waters  a  larger  amount  will  be  desirable ; 
and,  for  such,  1,000  cubic  centimetres  may 
be  adopted  as  a  convenient  unit. 

Experience  indicates  that  however  care- 
fully the  sand  may  be  placed,  the  filtration 
at  the  beginning  will  not  be  as  complete 
as  further  on  ;  and,  in  order  to  insure  the 
certain  removal  of  all  the  smaller  organ- 
isms, the  first  100  to  150  cubic  centimetres 
of  the  filtrate  is  returned  to  the  funnel 
and  passed  through  the  sand  a  second 
time.  The  funnel  is  allowed  to  stand 
until  the  completion  of  the  filtration,  when 
it  is  found  on  examination  of  the  filtrate 
that  nearly  every  organism  has  been  re- 
moved," and  we  have  the  result  that  the 
organisms  originally  contained  in  the  500 
cubic  centimetres  of  water  are  all  in  the 
sand  at  lower  end  of  funnel  stein.  The 
plug  of  wire  cloth  is  now  removed,  and 
the  sand  and  contained  organisms  washed 
with  5  cubic  centimetres  of  freshly  filtered 
water,  run  from  a  5  cubic  centimetre  pipette, 


69 


into  a  5  or  6  inch  test-tube.  The  test-tube 
is  slightly  shaken,  in  order  to  wash  all  the 
organisms  clear  from  the  sand.  The  sand, 
by  reason  of  greater  specific  gravity,  sinks 
quickly  to  the  bottom,  leaving  the  organ- 
isms distributed  through  the  water.  At 
the  instant  of  the  completion  of  the  set- 
tling of  the  sand  the  supernatant  water 
is  turned  into  another  smaller  test-tube, 
leaving  the  clean  sand  at  the  bottom  of 
the  first  tube.  We  now  have  the  organ- 
isms from  500  cubic  centimetres  of  water 
concentrated  into  5  cubic  centimetres  in 
the  second  tube,  from  which,  after  slight 
stirring,  to  insure  uniform  distribution,  1 
cubic  centimetre  is  taken  with  a  1  cubic 
centimetre  pipette,  and  transferred  to  a 
cell  50  by  20  millimetre  area,  and  exactly 
1  millimetre  in  depth.  Such  a  cell,  of 
course,  contains  1,000  cubic  millimetres,  or 
1  cubic  centimetre.  The  top  of  the  metal 
cell  is  ground  perfectly  smooth,  and  with 
a  little  practice  one  can  float  a  thick  cover- 
glass  to  place  without  losing  a  drop. 

The  next  step  is  the  enumeration.     This 
is  accomplished  by  transferring  the  cell  to 


70 


the  stage  of  a  microscope,  the  eye-piece  of 
which  is  fitted  with  a  micrometer,  so  ruled 
as  to  cover,  with  a  given  objective  and 
fixed  tube  length,  a  square  millimetre  on 
the  stage.  The  microscope  itself  is  fitted 
with  a  mechanical  stage  with  millimetre 
movement  in  both  directions  ;  and  for  this 
purpose  certain  simple  additions  have  been 
made  to  the  new  mechanical  stage  of  the 
Bausch  &  Loinb  Optical  Company,  by 
means  of  which  the  desired  result  is 
obtained  at  slight  expense.  The  count  is 
made  by  beginning  at  one  corner  of  the 
cell  and  going  systematically  over  the  area, 
in  accordance  with  such  a  formula  as  will 
insure  the  count  of  squares  selected  from 
every  part  of  the  slide  The  number  of 
squares  actually  counted,  will  depend  upon 
the  degree  of  accuracy  which  it  is  desired 
to  attain.  It  is  obviously  impossible  to 
count  the  1,000  squares  composing  the 
entire  area  of  the  slide ;  and  the  practical 
question  arises  as  to  just  what  multiple  of 
1,000  shall  be  used  to  secure  a  correct  aver- 
age. This  can  only  be  determined  by  trial 
and  comparison  upon  a  number  of  sam- 


71 


pies.  In  any  case,  not  less  than  20  squares 
should  be  counted,  and  if  time  will  possi- 
bly permit,  the  preference  should  be  in 
favor  of  always  counting  at  least  50. 

In  order  to  illustrate  the  matter,  a 
table  has  been  prepared,  which  represents 
the  area  of  the  cell  divided  into  1,000 
squares.  Brief  inspection  of  this  table 
will  show  the  difficulty  of  obtaining  true 
averages  when  only  20  squares  are  counted, 
and  exhibits  the  value  of  counting  the 
larger  number,  in  order  to  obtain  true 
averages. 

The  precise  millimetre  movement  of  the 
mechanical  stage  is  considered  a  matter 
of  considerable  importance,  and,  indeed, 
insisted  upon  as  an  integral  part  of  the 
method.  Without  it  the  tendency  will  be 
to  sometimes  select  squares  for  counting 
which  are  contiguous ;  while  at  other  times 
one  will  pass  over  squares  containing  few 
or  no  organisms  in  a  search  for  more  pro- 
lific ones,  making,  in  either  case,  an  error 
in  the  final  result.  By  use  of  the  mechani- 
cal stage,  with  a  definite  formula  for  pass- 
ing over  the  slide,  personal  errors  of  this 


72 


sort  are  eliminated,  leaving  only  those 
which  are  due  to  irregularity  of  distribu- 
tion of  the  organisms  in  the  water;  and  by 
always  stirring  thoroughly,  before  taking 
the  portion  for  examination,  with  1  cubic 
centimetre  pipette  this  error  may  also  be 
reduced  to  a  small  degree,  provided  as 
many  as  50  squares  are  counted  as  the 
basis  of  the  final  average.  Additional 
uniformity  of  distribution  of  organisms  in 
the  cell,  may  also  be  obtained  by  stirring 
gently  in  the  cell  itself  with  the  pointed 
end  of  the  pipette,  before  floating  the 
cover-glass  to  place ;  but  the  precaution 
should  always  be  taken  in  these  stirring 
operations  to  proceed  gently,  in  order  to 
guard  against  breaking  up  unnecessarily 
the  particles  of  amorphous  organic  matter, 
which  are  nearly  always  present  in  any 
sample  of  water  in  which  algous  growths 
and  decay  are  taking  place. 

The  definite  estimation  of  the  amor- 
phous organic  matter  is  a  thing  of  some 
difficulty ;  and  in  the  author's  use  of  this 
method  he  has  formed  a  sort  of  mental 
standard  as  to  the  unit  of  area  covered  by 


73 


one  mass  of  the  amorphous  matter.  Mr. 
Geo.  C.  Whipple,  who  assisted  in  the  work 
for  the  Boston  Water  Works,  has  sug- 
gested that  this  unit  be  made  definite  for 
all  persons,  by  taking  it  a  fixed  number  of 
square  microns ;  and  for  this  purpose  20 


FIG.  2. —  SECTION  OF  OPEN  CELL,  SHOWING  CURVE  OF 
SURFACE  OF  FLUID  DUE  TO  CAPILLARY  ATTRAC- 
TION AT  SIDES. 

seems  to  be  the  desirable  unit.  By  care- 
ful comparison  with  a  stage  micrometer 
for  a  few  times  this  unit  can  be  firmly 
fixed  in  mind,  and  an  estimate  of  the 
amount  of  amorphous  matter  made  with 
considerable  precision. 

The  advantage  of  a  cell  of  such  depth 
as  to  just  contain  the  quantity  taken  for 
examination  is  illustrated  by  Fig.  2, 
which  represents  the  open  cell,  and  shows 
the  meniscus  form  taken  by  the  liquid,  by 
reason  of  capillary  attraction  at  the  sides. 
This  curvature  is  so  considerable  as  to 
render  a  count  in  the  squares  near  the 


74 


edges  of  the  cell  impracticable,  for  optical 
reasons,  which  every  user  of  the  micro- 
scope will  readily  understand.  With  the 
covered  cell,  on  the  contrary,  the  count  may 
be  made  up  to  the  sides  as  easily  and  with 
-as  much  certainty  as  in  the  middle. 

The  placing  of  the  cover-glass  is  easily 
accomplished,  although  the  careful  observ- 
ance of  certain  details  are  essential  to 
uniform  success.  Thus,  the  cover-glass 
should  be  perfectly  clean,  and  just  before 
placing  should  be  moistened.  The  opera- 
tion of  putting  it  to  place  consists  in  lay- 
ing one  end,  held  in  a  horizontal  position, 
in  contact  with  the  ground  upper  surface 
of  the  metallic  portion  of  the  cell,  and, 
while  keeping  it  in  close  contact  at  all. 
points,  gradually  sliding  it  forward  until 
the  whole  ce.ll  is  covered. 

In  this  connection  it  may  be  noted  that 
cleanliness  is  quite  essential  in  all  these 
operations ;  and  the  hints  given  by  Dr. 
XfacDonald  in  his  Water  Analysis  fully 
cover  the  .case. 

In  the  original  cell,  as  designed  by 
Prof.  Sedgwick,  the  division  into  squares, 


75 


for  the  purpose  of  obtaining  the  rela- 
tion of  organisms  to  area,  was  arrived 
at,  as  already  stated,  by  ruling  square  mil- 
limetres upon  the  upper  surface  of  the 
glass  slide  on  which  the  cell  is  based. 
This,  however,  gives  a  unit  square  only 
for  the  bottom  of  the  cell ;  and  for  all 
organisms  at  the  top  of  the  liquid  no  unit 
of  area  is  obtained;  inasmuch  as  the  con- 
siderable change  of  focus  required  in  order 
to  see  them  at  all,  renders  it  impossible  to 
distinguish  the  ruled  lines  and  such  float- 
ing objects  at  the  same  time.  AVith  the 
eye-piece  micrometer,  however,  this  diffi- 
culty is  removed,  and  the  unit  square  is 
clearly  in  the  field  of  vision  without  ref- 
erence to  the  plane  in  the  cell  upon  which 
the  objective  is  focused. 

The  working  objective  for  these  counts 
may  be  either  a  two-thirds  or  one-half 
inch ;  and  for  identification  of  minute  un- 
known forms,  a  one-fourth  or  one-fifth 
water  immersion  capable  of  working 
through  a  thick  cover-glass,  and  cell  one 
millimetre  in  depth,  would  be  useful.  I 
have,  however,  no  experience  with  a  high- 


76 


power  objective  of  this  character,  and  can 
only  cite  the  opinion  of  the  Rochester 
opticians  that  such  an  objective  of  satis- 
factory correction  and  definition  can  be 
made. 

In  this  connection  it  may  be  mentioned 
that  Mr.  E.  Gundlach  has  made,  at  the 
author's  request,  a  dry  fourth  which  pos- 
sesses the  necessary  working  distance,  and 
is,  therefore,  easily  used  to  determine 
objects  at  the  very  bottom  of  the  cell, 
even  when  a  thick  cover-glass  is  in  place. 
Such  an  objective  is,  however,  doing  its 
work  through  three  mediums,  all  varying 
in  refractive  index ;  namely,  air,  glass,  and 
water,  and,  as  may  be  easily  predicated, 
the  trial  objective  is  not  entirely  a  success. 
The  angle  is,  of  course,  very  narrow,  though 
this  defect  is  inseparable  from  long  work- 
ing distance.  The  greatest  difficulty  is 
the  imperfection  in  the  correction  of  the 
chromatic  aberrations.  It  is  improve- 
ment in  this  direction  which  is  chiefly 
expected  to  result  from  the  use  of  a  water 
immersion.  The  dry  objective  is,  however, 
of  considerable  use  in  assisting  in  de- 


77 


termining  very  minute  objects  which 
present  only  a  simple  structure  ;  it  fails 
utterly  when  those  requiring  any  resolv- 
ing power  are  encountered. 

The  following  table  shows  the  compara- 
tive value  of  the  open  cell  with  mixed 
sand  and  organisms,  and  the  covered  cell 
with  sand  and  organisms  separated.  The 
results  are  in  number  of  organisms  per 
cubic  centimetre,  and  represent  only  the 
plant  forms  present  in  the  given  samples. 


0 

) 

(2 

) 

ORGANISMS. 

Open 

Closed 

Open 

Closed 

cell  with 

cell  with- 

cell with 

cell  with- 

sand. 

out  sand. 

sand. 

out  sand. 

Asterionella 

14 

30 

7 

23 

Tabellaria    . 

11 

21 

4 

15 

Cyclotella     . 

1 

1 

0 

2 

Anabaena    . 

2 

16 

7 

13 

Clathrocystis 
Coelosphaerium 

4 
5 

6 
12 

1 
5 

8 
3 

Nostoc      .    . 

0 

2 

1 

1 

Melosira  .    . 

2 

20 

1 

1 

Totals  .    .    . 

39 

108 

26 

66 

A  number  of  similar  comparative  counts 
have  been  made,  with  the  result  of   uni- 


78 


formly  getting  a  larger  number  of  or- 
ganisms by  the  Sedgwiek-Rafter  method. 

In  the  recently  published  Twenty- 
Second  Annual  Report  of  the  Massachu- 
setts Board,  it  is  stated  as  the  result  of  the 
various  comparisons  made  by  the  biolo- 
gists of  that  Board,  that  the  improvement 
in  processes  has  resulted  not  only  in  an 
increase  in  the  total  number  of  organisms 
found  in  a  given  water,  but  also  in  the 
number  of  genera.  Thus,  in  a  general  way, 
the  number  of  organisms  observed  by 
Prof.  Sedgwick's  original  sand  method  is 
several  times  that  observed  by  the  cloth 
method  of  Mr.  Parker;  likewise  the  number 
observed  by  the  Sedgwiek-Rafter  method 
is  probably  from  two  to  four  times  the 
number  observed  by  the  sand  method. 

The  foregoing  indicates  rather  briefly 
the  several  steps  taken  by  different 
workers  before  we  could  be  said  to  have  a 
practicable  method  of  making  the  micro- 
scopical examination  and  enumeration 
of  the  living  organisms  in  potable  water, 
which  fairly  met  all  the  conditions. 

The  author  hopes  that  some  worker  of 


79 


the  immediate  future  will  be  able  to  still 
further  advance  the  method  along  the  road 
to  ultimate  perfection. 

VALUE    OF     METHOD. 

The  value  of  a  method  of  this  character 
will  be  readily  recognized  by  all  who  un- 
derstand the  limitations  of  chemical  analy- 
sis, as  applied  to  the  decision  of  questions 
relating  to  the  sanitary  value  of  potable 
water.  The  most  useful  of  the  various 
chemical  methods  recognizes  in  effect  only 
two  classes  of  organic  impurity ;  namely, 
free  and  albuminoid  ammonia ;  and  groups 
every  organic  substance  occurring  in  water' 
as  one  or  the  other  of  these.  This  has  re- 
sulted in  the  condemning  of  the  waters  of 
mountain  streams  by  chemists,  who  ven- 
tured positive  opinions  as  to  sanitary  value 
on  the  evidence  of  chemical  analysis  alone. 
The  use  of  the  biological  method,  by  exhib- 
iting clearly  the  character  of  the  organic 
contamination,  will,  therefore,  lead  to  a 
more  accurate  knowledge  of  potable  waters 
than  can  be  gained  by  chemical  analysis. 

Moreover,  as  we  gain  more  knowledge  of 


80 


the  real  sanitary  significance  of  the  various 
forms  of  plant  and  animal  life,  the  daily 
or  weekly  fluctuations  in  quality  of  a  public 
water  supply  can  be  quickly  obtained  by 
the  use  of  this  method  of  biological  analy- 
sis ;  and  it  is  probable  that,  in  future,  public 
water  supplies  will  be  regularly  subject  to 
such  examinations. 

RESULTS. 

The  following  table  shows  a  number  of 
counts  of  samples  from  different  localities, 
and  illustrates  the  variations  in  number 


NO  OF 

SAMPLE. 

(1) 

(2) 

(3) 

<*) 

(5) 

(6) 

(7) 

(8) 

(9) 

(10) 

Sponge  Spicules 
Rhizopods    .     . 
Infusoria      .     • 
Rotifera  .     .     . 
Crustacea     .     • 

1 
0 
5 
1 
0 

1 
2 
2 
1 
0 

0 
0 
6 
0 
0 

0 
0 
80 
0 
0 

0 
0 
21 
3 
0 

1 
1 
50 
6 
1 

1 
0 
16 

1 
0 

0 
1 
0 
0 
0 

3 
1 

10 
2 
0 

0 
0 

11 

3 
0 

Total  Animals  . 

7 

6 

6 

80 

24- 

59 

18 

1 

16 

14 

Desmidieae    .    . 
Diatomaceae 
Zoospores     .     . 
Chlorophyceae 
Cyanophyceae    . 
Fungi       .     .    . 

0 
50 
130 
2 
15 
3 

1 
6 
51 

5 
38 

1 

1 
12 
73 
4 
70 
0 

0 

o 

280 
1 
4 
0 

3 
19 
244 
55 
157 
0 

4 
45 
88 
13 
110 
0 

5 
50 
2400 
1 
0 
0 

0 
8 
26 
0 
0 
0 

1 

17 
132 

1 
0 

1 

1 
35 
90 
5 

10 

2 

Total  Plants      . 

200 

102 

160 

287 

478 

260 

2456 

34 

152 

143 

Amorphous 
Matter  .     .     . 

80 

75 

140 

180 

238 

230 

45 

165 

170 

240 

81 


and  kind  of  organisms  found  in  various 
waters.  In  this  table  the  results  are 
grouped  in  classes  to  save  space,  and  are 
the  number  of  organisms  per  cubic  centi- 
metre, as  before. 

In  these  samples  (8)  is  from  a  spring, 
and  represents  very  pure  water.  All  of 
the  samples  except  (5),  (6),  and  (7)  are 
from  water  supplies,  and  represent  water 
of  medium  quality.  The  large  amount  of 
Cyanophyceaein  (5)  and  (6)  might,  of  itself, 
in  the  present  state  of  our  knowledge,  lead 
to  the  rejection  of  those  two  waters  as 
unfit  for  domestic  purposes,  especially  if 
continuous  observation,  extending  over 
two  or  more  seasons,  showed  that  such 
extensive  growths  occurred  frequently.  In 
all  such  cases,  however,  a  study  of  the 
environment  would  be  desirable  before 
making  a  final  decision,  and  it  is  not 
intended  to  say  positively  that  a  given 
sample  can  be  definitely  rejected  on  the 
evidence  of  the  microscopical  examination 
alone.  The  statement  may,  however,  be 
made  that  the  microscopical  examination 
will,  by  itself,  quite  as  frequently  furnish 


82 


definite  evidence  relative  to  the  suitable- 
ness or  unsuitableness  of  a  given  sample 
as  can  be  obtained  from  a  chemical  examin- 
ation alone  ;  while  the  microscopical  exam- 
ination in  conjunction  with  a  study  of  the 
environment  may  easily  furnish  decisive 
evidence  for  or  against.  This  latter,  state- 
ment may  be  applied  with  equal  force  to 
chemical  examinations  in  conjunction  with 
studies  of  the  environment ;  and  the  con- 
clusion is  therefore  reached,  that  in  rational 
water  analysis,  the  microscopical  examina- 
tion stands  on  a  par  with  the  chemical. 
This  interesting  and  highly  important  con- 
clusion has  been  fully  recognized,  as  already 
stated,  by  the  chemists  and  biologists  of 
the  Massachusetts  Board,  and  we  accord- 
ingly find  the  two  side  by  side  in  their 
recent  reports.  The  following  tabulations 
illustrate  a  typical  series  of  such  com- 
pound analyses  of  water  from  Eeservoir 
No.  4  of  the  Boston  Sudbury  Biver  Supply, 
extracted  from  the  Twenty-Second  Annual 
Beport  of  that  Board.  Moreover,  this  par- 
ticular series  is  of  special  interest  by  rea- 
son of  giving  the  results  continuously,  by 


83 


months,  for  a  year  and  a  half;  and  the 
movements  of  the  plant  and  animal  life  in 
conjunction  with  the  variation  in  the  am- 
monias, as  determined  chemically,  is  clearly 
shown,  not  only  in  a  plane  one  foot  below 
the  surface,  but  at  mid-depth  and  near  the 
bottom. 

In  order  to  illustrate  the  question  under 
discussion  fully,  the  series  also  includes 
the  examination  of  water  from  Cold  Spring 
Brook,  the  influent  stream  to  Eeservoir 
No.  4. 


84 


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DEDUCTIONS     FROM    THE    OBSERVATIONS    AT 
RESERVOIR  NO.  4. 

A  detailed  study  of  the  foregoing  series 
of  chemical  and  microscopical  analyses  at 
Reservoir  No.  4  reveals  a  number  of  im- 
portant points,  the  apparent  significance  of 
which  will  be  briefly  pointed  out. 

Eeservoir  No.  4,  situated  in  the  town  of 
Ashland,  on  Cold  Spring  Brook,  is  about 
three-quarters  of  a  mile  in  length,  and 
when  filled  to  the  ordinary  flow-line,  has  a 
depth  near  the  dam  of  about  forty-five  feet. 
It  is  nearly  two  thousand  feet  wide  at  the 
dam,  and  preserves  a  width  of  perhaps 
twelve  hundred  feet  to  near  the  upper  end. 
The  construction  was  completed  in  1885, 
and  the  reservoir  filled  for  the  first  time 
in  April,  1886.  The  bottom  was  thor- 
oughly cleaned  of  all  loam,  stumps,  and 
vegetable  matter,  and  the  margins  deepened 
wherever  the  original  marginal  depth  at 
high  water  was  less  than  eight  feet.  The 
water-shed  is  6.06  square  miles  area,  with 
few  inhabitants,  but  is  somewhat  swampy. 
The  storage  capacity  is  about  1,100,000,000 


101 

gallons  when  filled  to  the  ordinary  flow 
level. 

The  foregoing  series  of  analyses  of  water 
from  the  Cold  Spring  Brook,  are  of  samples 
taken  from  the  flowing  stream  a  short 
distance  above  the  head  of  Reservoir 
No.  4. 

The  samples  from  the  reservoir  itself 
were  taken  at  the  depths  indicated,  from  a 
point  about  mid-way  in  the  reservoir,  not 
far  from  the  dam.  ' 

As  stated  in  the  report,  the  microscopi- 
cal examinations  from  June,  1889,  to 
November,  1890,  inclusive,  were  made  by 
Prof.  Sedgwick's  sand  method;  while 
those  for  December,  1890,  were  made  by 
the  Sedgwick-Rafter  method.  This  may 
be  taken  as  partly  accounting  for  the  con- 
siderable increase  in  the  number  of  organ- 
isms tabulated  for  the  month  of  December, 
1890,  over  that  observed  in  November,  and 
the  months  immediately  preceding. 

While  the  results  obtained  are  of  great 
interest,  and  strongly  indicate  the  value  of 
the  microscopical  analysis  in  conjunction 
with  the  chemical,  it  may  nevertheless  be 


102 

observed  that  the  work  of  the  present 
year  will  be  likely  to  more  decisively 
exhibit  such  value ;  not  only  by  reason  of 
the  improvement  in  method  of  examination, 
but  because  of  the  increased  experience  of 
the  observers.  The  field  of  cryptogamic 
botany  and  zoology  necessary  to  be  covered, 
in  order  to  make  such  examinations  at  all, 
is  large ;  and  the  biologists  who  undertook 
to  make  these  studies  were  literally  explor- 
ing an  unknown  world.  That  their  work 
gives  very  satisfactory  results  at  this  early 
date,  can  only  be  taken  as  the  highest  pos- 
sible evidence  of  their  painstaking  in- 
dustry. The  work  itself  is  the  best 
exposition  of  the  new  views,  and  it  is 
unnecessary  to  consume  any  large  amount 
of  space  in  pointing  out  the  details.  A 
few  deductions  may,  however,  be  briefly 
noted : — 

The  running  water  of  Cold  Spring  Brook 
contained  a  number  of  species  of  Diatom- 
acese  \_Navicula,  Nitzckia,  Synedra],  which 
are  either  not  found  at  the  lower  end  of 
the  reservoir  at  all,  or  in  much  smaller 
number.  Of  these,  Navicula  and  Nitzchia 


103 

are  apparently  entirely  absent  from  the 
reservoir,  while  Synedra,  except  at  the  bot- 
tom, is  present  only  in  smaller  quantity. 
Thus  in  Cold  Spring  Brook  the  average 
number  per  month  of  Synedra,  per  cubic 
centimetre,  for  the  twelve  months  of  1890, 
is  found  to  be  8.8.  At  a  depth  of  one  foot 
below  the  surface  in  Reservoir  No.  4,  the 
average  number  per  month  of  Synedra  for 
the  same  period  is  5.6.  At  mid-depth  we 
find  4.0,  and  near  the  bottom  9.0,  Synedras 
per  cubic  centimetre. 

Collating  the  showing  for  Cydotella  in 
the  same  way,  we  find  the  form  entirely 
absent  from  the  Cold  Spring  Brook.  In 
the  reservoir  this  form  is  present  at  all 
depths,  only  in  the  months  of  June,  July, 
and  August ;  1890,  the  average  per  cubic 
centimetre  per  month  for  the  three  months 
being,  at  one  foot  below  the  surface,  49.0, 
at  twenty  feet,  127.0,  and  at  the  bottom 
18.0. 

Taking  the  whole  number  of  Diatomacece 
the  average  per  cubic  centimetre  per  month 
in  Cold  Spring  Brook  is  17.0 ;  at  one 
foot  below  the  surface  in  the  reservoir, 


104 


22.4;  at  twenty  feet,  42.5;   and  near  bot- 
tom, 20.0. 

Taking  the  total  number  of  plant  forms 
and  tabulating,  we  make  the  following 
showing :  — 


_; 

aJ 

o5 

LOCALITY. 

£ 
* 

,0 

1 

a 

1 

E 

fc£ 

37 

! 

0 

0 

I 

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Cold  Spring  Brook 
Reservoir  No.  4,  1 

3 

5 

« 

9 

34 

76 

60 

131 

15 

6 

,7 

76 

35.7 

foot  below  surface 

31 

2 

15 

13 

130 

215 

20 

44 

29 

11 

14 

152 

56.3 

Reservoir     No.     4, 

mid-depth      .     . 
Reservoir     No.     4, 

25 

3 

0 

9 

55 

129 

278 

27 

0 

6 

6 

195 

61.1 

near  bottom  .    . 

29 

4 

58 

4 

32 

32 

28 

22 

5 

6 

15 

167 

33.5 

From  this  table  it  is  clearly  apparent 
that  the  greatest  activity  of  the  micro- 
scopical plants  is  in  the  months  correspond- 
ing to  the  highest  temperature.  December 
we  may  leave  out  of  this  comparison,  as  by 
reason  of  the  increased  number  due  to  the 
change  in  method,  the  record  for  that  month 
is  probably  abnormal  so  far  as  the  balance  of 
the  series  is  cpncerned.  February  appears 
as  a  period  of  minimum  plant  life,  while 
October  and  November  are  also  low.  This 
is  as  might  be  expected  in  February,  though 


105 

the  record  here  gives  a  different  result  in 
October  and  November  from  the  author's 
experience  with  other  bodies  of  water  in 
which  the  microscopical  plant  life  has  been 
found  especially  vigorous  in  these  months. 
The  explanation  must  be  looked  for  in 
further  study  of  samples  from  Eeservoir 
No.  4,  though  a  partial  explanation  may 
be  inferred  by  studying  the  relations  of 
the  chemical  constituents  to  the  crypto- 
gamic  growths.  Such  relations  can  be 
more  conveniently  shown  by  diagrams  than 
by  either  tabulations,  or  written  descrip- 
tions ;  and  Plates  I.  to  IV.  have  accordingly 
been  prepared  for  this  purpose.  Studying 
them,  it  appears  that  in  Cold  Spring  Brook, 
and  also  in  the  reservoir,  at  both  surface 
and  mid-depth,  the  period  of  greatest  devel- 
opment of  plant  life  bears  a  clear  relation 
to  the  maximum  point  reached  by  the 
nitrates ;  the  same  may  also  be  affirmed  of 
the  results  of  the  examinations  of  samples 
near  the  bottom,  though  probably  some- 
what different  forces  are  at  work  near  the 
bottom  of  a  deep  body  of  water  from  those 
either  near  the  surface  or  at  mid-depth, 


106 

and  points  between.     The  nature  of  these 
forces  may  be  now  indicated :  — 

EFFECT    OF    LIGHT. 

The  chlorophylaceous  and  amylaceous 
plants  require  light  as  the  primary  condi- 
tion of  growth ;  and  if  we  assume,  for  the 
time  being,  a  fixed  condition  of  the  water 
at  various  planes,  we  may  say  that  the 
varieties  of  cryptogamic  plant  life,  which 
depend  upon  light,  will  decrease  as  we  go 
deeper  in  any  given  body  of  water,  in 
accordance  with  some  law  bearing  a  rela- 
tion to  the  intensity  of  light  at  the  given 
plane.  Changes  in  quality  of  light  as 
depth  increases  may  result  from  two  causes, 
or,  rather,  from  a  combination  of  two  causes. 
There  will  always  be  either  an  increased 
opacity  of  the  water  itself,  due  to  increase 
of  coloring  matter  as  the  depth  increases  ; 
or  where  the  coloring  matter  is  constant  at 
all  depths,  the  decrease  in  intensity  of 
light  will  be  in  accordance  with  the  general 
law,  that  intensity  decreases  geometrically 
as  distance  increases  arithmetically.  By 
way  of  illustration,  we  may  assume  the 


107 

opacity  of  a  given  body  of  water  to  be  such 
as  to  cut  off  ^  °f  fcne  total  intensity  of  light 
at  the  depth  of  one  foot.  We  have  then, 
after  passing  through  one  foot  of  such 
water,  Jg-  of  the  original  intensity  at  the 
surface.  In  passing  through  the  second  foot, 
the  light  again  loses  ^  of  the  total  quantity 
of  light  entering  the  second  foot,  or  •£$  of 
Jg.  At  the  depth  of  two  feet,  the  total 
intensity  is  therefore  |£J  of  the  original 
intensity,  and  so  on  for  any  depth  whatever. 
On  examining  the  color  column  in  the 
tables  of  results,  or  the  profile  of  the  same 
on  the  diagrams,  we  find  that  great  varia- 
tions in  color  occurred  in  the  water  of  Cold 
Spring  Brook,  the  color  determinations  run- 
ning all  the  way  from  3.50  in  August,  1889, 
to  0.30  in  August,  1890.  Also,  that  in 
June,  1890,  the  color  scale  stands  1.80. 
This  of  itself  represents  an  enormous  dif- 
ference in  the  plant-producing  capacity  of 
the  water  of  this  stream  between  June  and 
August,  1890,  and  by  itself  affords  a  partial 
explanation  of  why  the  plant  development 
in  August,  1890,  was  so  greatly  in  excess 
of  that  in  June.  Partial  explanation  is 


.  108 

stated  in  the  foregoing,  because  many 
other  circumstances  tend  to  modify  the 
results,  and  no  one  cause  can  be  assigned 
as  a  full  explanation. 

If  we  consider  the  color  scale  in  the 
results  for  Beservoir  No.  4,  one  foot  below 
the  surface,  we  find  that  the  range  in  vari- 
ation in  1890  was  from  0.35  in  August  and 
September,  to  0.85  in  November;  0.50 
being  the  figure  for  July  and  August  in 
that  year.  At  mid-depth  the  figures  for 
1890  show  0.60  for  June ;  0.50  for  July  ; 
0.40  for  August  and  September;  0.45  for 
October;  and  0.85  for  November.  Near 
the  bottom  they  are  0.70  for  May  and  June  ; 
0.40  for  July ;  0.35  for  August ;  0.50  for 
September  ;  0.55  for  October ;  and  0.85  for 
November.  The  relation  of  these  to  the 
other  results  are  also  clearly  indicated  on 
the  diagrams. 

Examining  the  tabulations  further,  it 
appears*  while  a  considerable  number  of 
chlorophylaceous  algae  (Chlorophyceae)  are 
found  at  mid-depth, '  the  number  is  still 
much  less  than  at  one  foot  below  the  sur- 
face; and  near  the  bottom,  the  numbers 


109 

run  generally  even  smaller.  This  is  as 
may  be  predicated  from  what  is  -known  in 
reference  to  the  influence  of  light  on  vege- 
tation. In  white  light  the  rays  of  different 
intensity  of  wave  motion  are  commingled 
in  such  manner  that  the  various-colored 
bands  of  the  spectrum  are  not  apparent. 
Such  light  is  normal  so  far  as  related  to 
physiological  action  on  the  processes  of 
vegetation.  The  chemical  changes  in  grow- 
ing plants,  however,  are  chiefly  due  to  the 
rays  of  inferior  wave  motion.;  as,  for  in- 
stance, the  red,  orange,  yellow,  or  green. 
The  mechanical  changes,  on  the  other  hand, 
are  produced  by  the  rays  of  high-wave 
motion,; — the  blue,  violet,  or  ultra-violet. 
The  former  are  chiefly  concerned  in  the 
production  of  chlorophyl,  the  decomposi- 
tion of  carbon  dioxide,  and  the  formation 
of  starch.  The  latter  influence  the  rapid- 
ity of  growth,  alter  the  movements  of 
protoplasm,  compel  swarm-spores  to  adopt 
a  definite  direction  in  their  motion,  change 
the  tension  of  the  tissues  of  the  motile 
organs,  and  hence  affect  their  position,  etc.* 

*  Sachs'  Botany,  p.  778.32» 


110 

Again,  the  action  of  light  on  plants  is  in 
proportion  to  its  intensity.  This  question 
is  one  with  more  than  theoretical  interest, 
as  is  sufficiently  shown  by  considering  that 
the  production  of  starch  in  the  chlorophy- 
laeeous  algae  is  dependent  upon  the  quan- 
tity of  light  which  the  plants  receive.  All 
the  free-floating  forms  are  from  a  variety 
of  causes  ;  as,  for  instance,  changes  of  tem- 
perature, cessation  of  the  production  of  gas 
by  the  plants  themselves,  etc. ;  quite  sus- 
ceptible to  changes  in  specific  gravity,  and, 
therefore,  at  different  times,  occupy  differ- 
ent levels  in  the  water.  In  light  of  less 
than  a  certain  degree  of  intensity  the 
starch  is  not  formed;  the  protoplasmic 
matter,  which,  with  sufficient  intensity  of 
light,  would  go  to  the  production  of  starch, 
remains  protoplasmic.  Again,  if  algae,  in 
which  starch  is  fully  formed,  are  placed  in 
the  dark,  or  in  light  of  less  than  the  starch- 
producing  degree  of  intensity,  the  starch 
already  formed  will  disappear;  such  changes 
taking  place  as  restore  the  starch  material 
to  its  original  state.  On  being  again 
brought  into  strong  light,  the  starch  will 


Ill 

reform,  and  by  treatment  in  a  suitable  cul- 
ture-cell, all  these  formations  can,  under 
proper  gradation  of  light,  be  observed  for 
a  considerable  length  of  time. 

The  application  to  be  made  of  these 
observations  is  in  relation  to  the  changes 
in  intensity  of  the  light  which  will  exist 
at  different  depths  in  any  given  body  of 
water,  and,  consequently,  in  relation  to  the 
varying  quality  of  the  water  itself  at  dif- 
ferent depths.  In  this  connection  it  is- 
important  to  clearly  understand  that  the 
production  of  chlorophyl  and  starch  is  very 
intimately  related  to  the  chemical  compo- 
sition of  water,  and  that  if  such  conditions 
obtain  as  preclude  the  continuance  of  their 
formation,  changes  in  chemical  composition 
may  be  expected  to  result. 

This  phase  of  the  subject  could  be  pur- 
sued indefinitely,  but  the  limits  of  a  vol- 
ume of  the  Science  Series  clearly  will  not 
permit.  The  foregoing  is  a  skeleton  merely  ; 
and  the  reader  who  cares  to  pursue  the 
subject  further  must  consult  the  great 
works  of  Sachs'.32aandb 


112 

EFFECT    OF    TEMPERATURE. 

The  most  important  law  of  temperature 
in  relation  to  plant  life  with  which  we  are 
concerned,  in  an  investigation  of  the 
relation  of  cryptogamic  growths  to  the 
purity  of  a  natural  water,  is  that  affirm- 
ing, that  in  plant  growth  the  exercise  of 
every  function  is  restricted  to  certain 
definite  limits  of  temperature,  within 
which  it  alone  can  take  place.* 

A  corollary  to  the  foregoing  may  be 
stated  as  follows  :  the  functions  of  a  plant 
are  assisted  and  accelerated  in  their  in- 
tensity when  the  temperature  rises  above 
the  lower  limit  for  that  function ;  on 
reaching  a  definite  higher  degree,  a  maxi- 
mum of  intensity  is  attained,  the  activity 
then  decreases  with  a  further  increase  of 
temperature,  until  it  entirely  ceases  at 
the  upper  limit.! 

As  a  brief  deduction  from  the  foregoing 
law,  it  may  be  assumed  that  some  plants 
(and  the  assumption  is  apparently  en- 
tirely true  as  applied  to  cryptogams)  will 

*  Sachs'  Botany,  p.  727.  t  LOG.  cit.,  p.  729. 


grow  best  in  low  temperatures,  others  in 
high  temperatures,  the  latter  being  much 
the  more  numerous  in  this  latitude.  Or- 
dinarily, therefore,  the  lowering  of  the 
temperature  of  a  body  of  water,  as  winter 
approaches,  will  be  accompanied  by  a  de- 
crease in  the  amount  and  variety  of  micro- 
scopical life.  Exceptions  to  this  rule  may, 
however,  be  expected  by  reason  of  certain 
forms  flourishing  in  a  low  temperature. 

Again,  in  very  large  and  deep  bodies  of 
water  it  is  necessary  to  go  only  a  few  feet 
(50  to  80)  below  the  surface  before  a  level 
is  reached  in  which  the  temperature  is 
practically  constant  throughout  the  whole 
year.  In  such  a  body  the  few  observations 
that  have  been  thus  far  made,  indicate  an 
abundant  development  of  both  plant  and  4 
animal  life  in  winter.  This  is  finely  shown 
by  Mr.  Vorce  in  his  paper  on  Forms  Ob- 
served in  Water  of  Lake  Erie,25  where  are 
figured  and  described  in  the  first  part,  one 
hundred  and  ninety-two  species  of  plants 
and  animals,  all  observed  between  Dec.  25, 
1880  and  Jan.  22,  1881.  A  study  of  Lake 
Erie  water  for  several  years  by  Mr.  Vorce, 


114 

indicated  the  appearance  of  certain  forms 
at  about  the  same  time  every  year.  This 
observation  as  to  periodicity  of  forms  has 
been  verified  by  the  author  in  his  studies 
of  the  water  of  Hemlock  Lake. 

In  smaller  bodies  of  water,  like  Reservoir 
No.  4  of  the  Boston  supply,  it  is  uncertain 
that  any  such  permanency  and  periodicity 
of  the  winter  forms  are  maintained.  Addi- 
tional study  is  necessary  to  elucidate  this 
point. 

PHYSICAL    CONDITION    OF    THE    WATER. 

From  the  preceding,  it  is  evident  that 
in  generalizing  the  results  of  these  ex- 
aminations, it  must  be  borne  in  mind  that 
April,  May,  and  June  are  months  of 
1  increasing  temperature  ;  July,  August,  and 
September  months  of  maximum  tempera- 
ture ;  October,  November,  and  December 
months  of  decreasing  temperature ;  and 
January,  February,  and  March  the  months 
of  minimum  temperature.  The  general  ef- 
fect of  these  changes  on  the  quantity  and 
quality  of  the  microscopical  life  has  been 
already  briefly  indicated  ;  it  now  remains 


115 

to  point  out  an  important  series  of  changes 
in  the  body  of  water  itself,  due  to  the 
fluctuations  of  temperature. 

In  the  first  place,  in  summer  the  mean 
temperature  of  shallow  bodies  of  water 
will  generally  be  higher  than  that  of 
deeper  ones;  this  temperature  will  be 
more  quickly  reached  in  the  months  of 
increase,  and  more  quickly  lost  in  the 
months  of  decrease.  In  winter  the  shal- 
low body  will  usually  exhibit  a  some- 
what lower  temperature  than  the  deeper 
one. 

Again,  as  cold  weather  approaches,  in 
the  fall,  the  upper  layers  of  a  body  of 
water  become  cooler  than  the  layers  im- 
mediately below ;  and  there  accordingly 
results,  by  reason  of  gravitation,  a  com- 
plete vertical  circulation,  through  the  influ- 
ence of  which  the  relative  positions  of  the 
top  and  bottom  layers  are  reversed,  down 
to  a  depth  where  the  temperature  may  be 
expected  to  remain  uniform  for  the  whole 
year.  By  way  of  illustrating  the  extent 
of  the  force  producing  this  overturning  in 
the  fall,  the  following  table  of  relative 


116 

density  and  weight  of  a  cubic  foot  of 
water,  at  different  temperatures,  is  in- 
serted.* 


1  Tempera- 
ture. 

Relative 
Density. 

*°* 

^5  OT3 

2fe  « 
4s  2 

m 

32° 

.99987 

62.416 

35° 

.99996 

62.421 

39°.  3 

1. 

62.424 

45° 

.99992 

62.419 

50° 

.99975 

62.408 

55° 

.99946 

62.390 

60° 

.99907 

62.366 

65° 

.99859 

62.336 

70° 

.99802 

62.300 

75° 

.99739 

62.261 

80° 

.99669 

62.217 

July  4, 1889,  Desmond  FitzGerald,  C.  E., 
and  the  author  made  a  number  of  measure- 
ments of  the  temperature  of  Lake  Cochit- 
uate,  at  a  depth  of  sixty  feet.  A  mean 
of  several  of  the  observations  gives  a 

*  Smith's  Hydraulics,  p.  14. 


117 

temperature  at  that  depth  of  45°. 4 ;  the 
change  at  points  a  short  distance  apart 
being  from  44°.2  to  47°0.  The  surface 
temperature  at  the  point  of  making  the 
observations  was  75°.6,  the  air  being  77°. 2. 
From  the  foregoing  table,  it  appears  that 
a  cubic  foot  of  water  at  45°  weighs 
62.419  pounds  ;  and  at  a  temperature  of 
75°  the  weight  is  62.261  pounds,  giving  a 
difference  at  these  temperatures  of  0.158 
pounds. 

It  is  clear,  therefore,  that  at  this  time  of 
year  the  bottom  layers  were  certain  to 
remain  at  the  bottom,  by  virtue  of  superior 
gravity.  On  the  approach  of  cold  weather, 
however,  the  decrease  in  temperature  at 
the  surface  increases  the  density  there, 
gradually  leading  to  a  complete  vertical 
circulation,  as  already  indicated. 

Again,  in  shallow  bodies  of  water  we  may 
further  occasionally  have  a  vertical  circu- 
lation,—  from  bottom  to  top, — due  to  the 
influence  of  heavy  winds  ;  and  the  upper 
layers  of  a  large  and  deep  body  may  also 
be  expected  to  respond  to  the  same  source 
of  discrepancy. 


118 

All  these  various  modifying  influences 
must  be  taken  into  account  in  studying  the 
results  of  water-supply  examinations. 

LUDLOW    RESERVOIR,    SPRINGFIELD. 

The  main  source  of  supply  to  the  city  of 
Springfield,  Massachusetts,  is  derived  from 
the  Ludlow  Storage  Reservoir.  The 'area 
when  filled,  is  about  445  acres,  and  the 
total  content  1,992,000,000  gallons.  The 
reservoir  was  constructed  about  1875,  and 
during  every  summer  since,  the  water  has 
been  unpleasantly  affected  with  bad  tastes 
and  odors.  The  greatest  depth  is  about 
twenty-four  feet,  with  an  average  of  nearly 
fourteen  feet.  Of  the  area  flowed  by  the 
reservoir,  two  hundred  and  eighty-one  acres 
were  covered  with  forest,  a  portion  of 
which  was  swampy  land  with  peaty  de- 
posits, from  six  inches  to  four  feet  in  depth. 
The  peaty  areas  are  all  at  least  twelve  feet 
below  the  flow-line,  and  many  of  them 
sixteen  feet  below.  All  trunks  of  trees 
and  brush  were  burned,  and  stumps  cut 
low  and  charred.  Nearly  six  and  one-half 
acres  of  the  most  objectionable  portion  of 


119 

the  swamp  were  sanded  over  to  a  depth 
of  about  one  and  one-half  feet.  The  shores 
are  mostly  abrupt,  the  only  exception  be- 
ing a  small  shallow  area  at  the  upper  end. 

The  original  plan  included  the  uniting 
of  several  water-sheds  by  canals  ;  and  the 
total  tributary  area  was  6,484  acres.  In 
1886  a  portion  of  this  was  cut  off,  leaving 
at  the  present  time  4,358  acres,  on  which 
there  is  only  a  very  small  population.* 

The  chemical  and  microscopical  analyses 
recorded  in  the  following  tables  are  of  the 
greatest  interest,  as  showing  the  relation 
between  the  high  ammonias  and  the  ex- 
cessive development  of  plant,  and,  at  times, 
of  animal  life.  These"  relations  are  so 
clearly  shown  by  the  tables  and  diagrams 
that  an  extended  discussion  may  be  omitted. 
A  few  points  only  will  be  noted.  In  the 
first  place,  the  reader's  attention  is  directed 
to  the  fact,  that  during  the  whole  time 
covered  by  these  tables,  this  -water  has 
been  in  constant  use  for  domestic  purposes 
in  the  city  of  Springfield;  the  total  con- 
sumption for  all  purposes  being  about 
4,000,000  gallons  per  day. 

*  Special  Report,  Tart  I.,  pp.  296-7. 13c 


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DEDUCTIONS     FROM      THE      LUDLOW     RESER- 
VOIR   DIAGRAM. 

A  study  of  the  diagram  of  the  results  of 
the  chemical  and  microscopical  examina- 
tions, Plate  V.,  of  water  from  six  feet 
below  the  surface  of  Ludlow  B/eservoir, 
further  elucidates  a  number  of  points  of 
interest  in  relation  to  the  connection  be- 
tween the  light  transmitting  capacity  of 
water,  and  the  production  of  excessive 
growths  of  microscopical  plants  and  ani- 
mals. One  explanation  of  such  growths 
has  been  what  may  be  termed  the  theory  of 
sufficiency  of  food ;  according  to  which,  it 
is  assumed  that  excessive  developments  of 
any  given  organism  can  only  occur  in  a 
particular  locality,  when  the  kind  of  food 
required  by  the  organism  is  present  in 
that  locality  in  sufficient  abundance  to 
nourish  the  developing  form.  This  theory, 
while,  as  a  general  proposition  essentially 
true,  is  still,  by  reason  of  the  existence  of 
a  number  of  modifying  elements,  hardly 
a  full  explanation  of  all  the  attending  phe- 
nomena, as  may  be  briefly  pointed  out. 


129 

The  so-called  free  ammonia  and  the 
mineral  nitrates,  are  the  two  chemical 
constituents  which  contribute  most  exten- 
sively to  the  nourishment  of  minute  plants 
in  potable  water.  Both  of  these  are  rela- 
tively low  in  Ludlow  Reservoir,  for  the 
whole  time  covered  by  these  observations. 
If,  however,  we  examine  the  relation  of 
the  color  line  on  the  diagram  to  that  of 
the  Diatomaceae,  Chlorophyceae,  Cyanophy- 
ceae.  and  Infusoria,  we  discover  that  the 
several  maximum  developments  of  micro- 
scopical life  have  all  occurred,  either 
when  the  color  scale  was  decreasing,  or  at 
or  near  a  minimum.  In  no  case  during  the 
period  from  June,  1889,  to  December*  1890, 
has  there  been  an  excessive  development 
of  life  while  the  color  scale  was  high. 
Again,  a  rise  in  the  color  scale  has  appar- 
ently been  followed,  usually,  by  a  decrease 
in  the  number  of  organisms.  Again,  in 
August,  1890,  a  rise  of  the  Diatomaceae  to 
1,950  per  cubic  centimetre,  was  nearly  co- 
incident with  a  fall  of  the  color  scale  from 
0.50  to  0.15.  If  we  examine  other  tabula- 
tions of  large  developments  of  minute  life, 


130 

as  given  in  the  Report  of  the  Massachu- 
setts Board,  we  find  a  number  of  confir- 
mations of  the  general  law  here  indicated. 
Some  exceptions  are  also  found,  but  the 
evidence  in  favor  is  apparently  somewhat 
in  excess  of  that  against. 

A  study  of  the  several  tables,  in  refer- 
ence to  the  point  under  discussion,  indi- 
cates, further,  that  the  excessive  growths 
of  microscopical  life  have  usually,  thus  far, 
occurred  in  Massachusetts  in  waters  of 
relatively  low  color  scale ;  a  point  which, 
if  found  true  on  further  study,  must  be  set 
down  to  the  credit  of  the  colored  waters, 
as  indicating  that  they  are  somewhat  less 
liable  to  sudden  deteriorations  of  taste 
and  odor  than  the  colorless  or  so-called 
white  waters.  The  whole  subject  of  plant 
and  animal  development  in  potable  waters 
is,  however,  still  in  its  infancy,  and  pro- 
visional conclusions  can  only  be  drawn  at 
present.  It  is  not  intended,  therefore,  to 
assert  that  the  law  of  development  of 
minute  forms  in  an  inverse  ratio  to  the 
amount  of  color  is  yet  fully  proven.  Its 
demonstration,  if  made  at  all,  will  follow 


131 

from  further,  and  more  accurate  and  elabo- 
rate, tabulations  of  the  amount  of  minute 
life.' 

The  question  may,  however,  be  very 
appropriately  asked,  why  the  theory  of 
sufficiency  of  food  does  not  fully  explain 
the  cause  of  the  excessive  development 
which  regularly  takes  place  not  only  in  the 
Ludlow  Reservoir,  but  in  many  other 
similar  bodies  of  water  ? 

A  complete  answer  will  lead  to  the  con- 
sideration of  somewhat  profound  questions 
in  relation  to  the  reproduction  and  devel- 
opment of  the  Protophyta  and  the  Pro- 
tozoa,' and  will  indeed  lead,  figuratively, 
into  rather  deep  water.  The  question  was, 
however,  ably  discussed  by  Alexander 
Braun,  forty  years  ago,  in  his  "Rejuven- 
escence in  Nature."  "  Braun  takes  up  the 
question  more  especially  in  its  relation  to 
the  life  and  development  of  plants,  and 
shows  that  among  the  cryptogams,  at  any 
rate,  there  are  alternating  periods,  on  the 
one  hand,  of  moderate  reproduction,  and, 
on  the  other,  of  extraordinary  reproduc- 
tion ;  that  during  the  first  period,  the  life 


132 

forces  of  the  plant  are  gradually  conserv- 
ing themselves  for  the  necessarily  excess- 
ive effort  required  in  the  second.  There 
is,  therefore,  an  alternation  of  generations, 
the  respective  periods  of  which  are  as  yet 
indeterminate ;  and  we  may  conclude  that 
the  excessive  development  of  minute  life 
which  has  characterized  water-supplies 
suffering  from  bad  tastes  and  odors,  is 
merely  a  manifestation  of  one  phase  of 
such  alternation  ;  but  why,  in  many  cases, 
occurring  at  irregular  intervals,  we  are,  as 
yet,  unable  to  definitely  say. 

An  explanation  of  this  irregularity  of 
appearance  of  these  troubles  may  be  found 
in  the  case  of  some  of  the  Cryptogams,  in 
the  consideration  that  the  spores,  after  a 
period  of  activity,  enter  into  a  resting 
state,  and  only  re-awaken  to  a  new  life 
after  more  or  less  complete  desiccation 
and  resubjection  to  moisture.  It  is  quite 
possible,  in  this  view,  that  many  years 
may  intervene  between  periods  of  such 
disturbances  of  a  water  supply  by  any 
given  cryptogam. 

Returning  for  a  moment  to  the  subject 


133 

of  colored  water,  the  statement  can  be  now 
made,  that  while  a  given  colored  water 
may  be  the  subject  of  an  excessive  devel- 
opment of  plant  life,  nevertheless,  other 
things  being  equal,  the  development  would 
be  for  many  species  more  pronounced, 
when  once  started,  in  either  a  colorless 
water  or  one  of  low  color  scale,  than  in 
waters  of  high,  or  relatively  high,  color 
scale.  The  decrease  in  intensity,  or  the 
modification  in  quality,  of  light,  resulting 
from  the  presence  of  the  coloring  matter 
may  be  expected  to  exert  a  modifying  in- 
fluence on  the  activity  of  any  given  crypto- 
gamic  development. 

In  reference  to  the  Ludlow  Eeservoir  it 
may  be  said,  by  way  of  concluding  the 
subject,  that  the  old,  swampy  bottom  of 
this  reservoir  must  be  considered  as  un- 
favorable for  maintaining  a  high  degree  of 
freedom  from  cryptogamic  growths.  Such 
a  location  may  be  expected  to  contain  the 
accumulated  resting  spores  of  various 
Cryptogams  for  many  years.  The  origi- 
nal flooding  of  the  reservoir  started  this 
accumulation  of  resting  spores  into  vigor- 


134 

cms  life ;  the  energy  of  the  development 
being  possibly  proportionate  to  length  of 
the  period  of  rest.  The  original  construc- 
tion should,  therefore,  have  included  the 
sanding  of  the  entire  bottom  to  the  depth 
of  at  least  two  feet,  instead  of  the  worst 
portions  to  the  depth  of  a  foot  and  a  half. 
The  existing  conditions  can  probably  be 
improved  by  correcting  the  shallow  flow- 
age  at  the  upper  end,  and  keeping  the 
reservoir  as  nearly  full  as  possible  :  we 
thereby  eliminate  the  opportunity  which 
now  exists  for  an  annual  desiccation  and 
revivification  of  spores.  Systematic  obser- 
vations of  the  kind,  made  in  X1889  and 
1890,  will  be  likely,  then,  to  determine  if 
any  marked  decrease  in  number  and  vari- 
ety of  organisms  is  taking  place,  as  may 
be  expected  if  the  foregoing  theory  is 
approximately  true.  It  is,  however,  ex- 
ceedingly doubtful  if  there  will  be  any 
marked  improvement  so  long  as  the  alter- 
nate covering  and  uncovering  of  the  shal- 
low portions  at  the  upper  end  furnishes 
annually  the  ideal  conditions  for  active 
cryptogamic  development.  All  that  can 


135 

be  hoped  for,  with  present  conditions,  is 
that  the  generations  of  little  plants  and 
animals  may  in  time  exhaust  themselves  : 
as  yet  there  is  absolutely  no  data  for  pre- 
dicting when  this  will  take  place. 

The  water  supply  of  Brockton,  Mass., 
presents  a  case  of  a  water  in  which  the  color 
is  usually  high  (the  minimum  from  June, 
1889,  to  December,  1890,  is  0.45>  the  maxi- 
mum 1.30,  and  the  mean  0.85),  and  which 
is  also  the  source  of  an  abundant  crypto- 
ganiic  life.  A  comparison  of  the  tabula- 
tions indicates  that  here,  also,  the  general 
law  of  relation  of  the  development  of  the 
plants  to  intensity  of  light,  as  indicated 
by  the  color  scale,  is  found  to  fairly  hold 
good  as  shown  in  the  case  of  Ludlow  Res- 
ervoir. 

The  foregoing  is  a  skeleton  of  the  new 
art  of  the  quantitative  microscopical  exam- 
ination of  potable  water.  The  list  of 
literature  will  show  the  several  sources  of 
useful  information. 


LITERATURE. 


THE  following  list  of  books,  journals, 
and  miscellaneous  papers  does  not  in  any 
sense  exhaust  the  several  subjects.  With 
three  or  four  exceptions  it  includes  only 
those  either  in  the  author's  own  collection, 
or  to  which  he  has,  at  various  times,  had 
access.  A  considerable  number,  both  of 
books  and  papers  of  little  value  for  actual 
work  at  the  present  time,  have  been 
omitted ;  and  the  list  may,  therefore,  be 
taken  as  including,  so  far  as  the  author 
can  judge  from  his  own  experience,  only 
those  likely  to  be  of  utility,  either  in 
studying  the  sanitary  relations  and  biology 
of  a  public  water  supply  and  cognate  ques- 
tions, or  in  making  the  microscopical  ex- 
amination of  potable  water.  Those  who 
desire  a  more  complete  bibliography  are 
referred  to  the  volumes  in  the  following 
list,  which  are  specially  indicated  by  the 
double  asterisks  thus,**  where  exhaust- 
137 


138 

ive  lists  of  the  several  special  subjects 
may  be  found.  The  Natural  History  Cata- 
logues of  W.  P.  Collins,  157  Great  Port- 
land Street,  London,  W.,  may  also  be 
profitably  consulted  for  lists  of  books  and 
papers  on  the  various  forms  of  micro- 
scopical life. 

A  very  few  books  on  the  microscope 
-are  included  in  this  list,  to  which  the  ob- 
jection may  be  made,  that  they  are  of  a 
popular  character  rather  than  scientific. 
To  this  objection  it  may  be  stated,  that  all 
such  which  are  included  have  been  of  use 
to  the  author  by  furnishing  some  fact  not 
found  elsewhere  ;  and  it  is  with  the  ex- 
pectation that  they  may  be  of  similar  use 
to  others  that  they  appear  here. 

I. — WATER    IN    ITS  CHEMICAL,  BIOLOGICAL, 
AND    SANITARY    RELATIONS. 

1.  Blyth,  A.  W. :  A  Manual  of  Public 
Health.     8vo,  London,  Macmillan  &  Co., 
1890. 

2.  Buck,  A.  H. :  A  Treatise  on  Hygiene 
and   Public   Health.      2   vols,   8vo,   New 
York,  Wm.  Wood  &  Co.,  1879. 


139 

3.  Chambe.rlain,  C.  W. :  Organic  Impuri- 
ties  in   Drinking  Water.     Paper  in    An. 
Kept,  of  Conn.  St.  Bd.  Health,  1883,  pp. 
259-280. 

3^.  Cohn,  F. :  Ueber  den  Brunnenfaden 
(Crenothrix  polyspora),  mit  Bemerkungen 
iiber  die  Mikroscopische  Analyse  des  Brun- 
nenwassers.  In  Beitrage  zur  Biologie  der 
Pflanzen,  1870. 

4.  Davis,  Floyd :  An  Elementary  Hand- 
book of  Potable  Water.      12 mo,   Boston, 
Silver,  Burdett,  &  Co.,  1891. 

5.  Drown,    T.  M. :    (a)    The  Color  and 
Odor  of  Surface  Waters.     Jour.  New  Eng. 
W.  Wks.  Assn.,  March,  1888. 

(b)  The  Filtration  of  Natural  Waters. 
Jour.  Assn.  of  Eng.  Socs.,  1890 ;  also,  Jour. 
New  Eng.  W.  Wks.  Assn.  Dec.,  1890. 
[For  further  on  the  same  subjects,  by 
Dr.  Drown,  see  Special  Report'  Mass. 
Board,  1890,  Part  L] 

6.  Frankland,  E. :   Water  Analysis  for 
Sanitary   Purposes.      12mo,  Philadelphia, 
P.  Blakiston,  1880. 

7.  Hassall,  A.   H. :    (a)  A  Microscopic 
Examination  of  the  Water  supplied  to  the 


140 

Inhabitants  of  London  and  the  Suburban 
Districts.     London,  1850. 

(b)  Food :  Its  Adulterations  and  the 
Methods  for  their  Detection.  12mo, 
London,  Longmans,  Green,  &  Co.,  1876. 

8.  Hirt,  L. :  Ueber  den  Principien  und 
die  Methode  der  Mikroscopischen  Unter- 
suchung    des    Wassers.      Zeitschrift    fiir 
Biologie,  1879. 

8J.  Hulwa,  F. :  Beitrage  zur  Schwem- 
menkanalization  und  Wasser-Versorgung 
der  Stadt  Breslau.  Centralblatt  ftir  allge- 
meine  Gesundheitspflege,  Erganzungshefte, 
1885. 

9.  Kean,  A.  L. :  A  New  Method  for  the 
Microscopical  Examination  of  Water.    Sci- 
ence, Feb.  15,  1889.     Eng.  News,  March 
30,  1889. 

10.  Leeds,  A.  R,. :  Reports  on  the  Water 
Supply  of  Philadelphia. 

(a)  Eeport  on  the  Condition  of  the 
Schuylkill  River  in  January,  1883.  An. 
Rept.  Chf.  Eng.,  Phil.  W.  Dept.,  1883,  pp. 
343-372. 

(6)  Preliminary  Eeport  of  a  Chemical 
Investigation  into  the  Present  and  Pro- 


141 

posed  Future  Water  Supply  of  Philadel- 
phia. An.  Kept.  Chf.  Eng.,  Phil.  W. 
Dept.,  1883.  pp.  231-262. 

(c)  Eeport   of   Progress  of   a  Chemical 
Investigation,  etc.,  W.  Sup.  of  Philadelphia. 
An.  Kept.  Chf.  Eng.,  1884,  pp.  353-381. 

(d)  Final  Eeport  of  a  Chemical  Investi- 
gation, etc.,  W.  Sup.  of  Philadelphia.  An. 
Kept.  Chf.  Eng.,  1885,  pp.  379-400. 

11.  Left'man    and    Bean :    Examination 
of  Water  for  Sanitary  and  Technical  Pur- 
poses.     12mo,  'Philadelphia,  P.  Blakiston 
.&  Co..  1889. 

12.  Mallet,  J.  W. :  Eeports  (1),  (2),  (3), 
On  the  Eesults  of  an  Investigation  as  to 
the  Chemical  Methods  for  the  Determina- 
tion of  Organic  Matter  in  Potable  Water. 
An.  Eept.  Nat.  Bd.  Health  for  year  ending 
June  30,  1882,  pp.  184-354. 

13.  Massachusetts      State      Board      of 
Health,  Eeports.     Boston,     (a)    On  Some 
Impurities  of  Drinking  Water  caused  by 
Vegetable    Growths,    by    W.    G.   Farlow. 
Supplement  for  1879,  pp.  131-152. 

(b)  Eeport    of    the    Biologist,     G.     H. 
Parker.     Nineteenth  An.  Eept. 


142 

(c)  Special  Report  on  Water  Supply 
and  Sewerage,  1890.  Part  I.  contains : 
(1)  The  Chemical  Examination  of  Waters 
and  the  Interpretation  of  Analyses,  by  Dr. 
T.  M.  Drown ;  (2)  Report  upon  the  Organ- 
isms, excepting  the  Bacteria,  found  in  the 
Waters  of  the  State,  by  GL  H.  Parker; 
(3)  Summary  of  Water  Supply  Statistics, 
by  F.  P.  Stearns;  (4)  Classification  of 
Drinking  Waters  of  the  State ;  (5)  Special 
Topics  Relating  to  the  Quality  of  Public 
Water  Supplies,  by  Messrs.  F.  P.  Stearns 
and  Dr.  T.  M.  Drown ;  and  (6)  the  Pollu- 
tion and  Self-Purification  of  Streams,  by 
F.  P.  Stearns. 

Part  II.  contains :  (1)  A  Report  of  the 
Chemical  Work  of  the  Lawrence  Experi- 
ment Station,  including  Methods  of  Analy- 
sis, and  some  Investigations  of  the  Process 
of  Nitrification,  by  Messrs.  Dr.  T.  M.  Drown 
and  A.  Hazen;  (2)  A  Report  of  the  Bio- 
logical Work  of  the  Lawrence  Experiment 
Station,  including  an  account  of  Methods 
Employed  and  Results  Obtained  in  the 
Microscopical  and  Bacteriological  Investi- 
gations of  Sewage  and  Water,  by  Wm.  T. 


143 

Sedgwick;  (3)  Investigations  upon  Nitrifi- 
cation and  the  Nitrifying  Organism,  by 
E.  0.  Jordan  and  Ellen  H.  Kichards.  (In 
addition,  the  general  subject  of  water  sup- 
ply, its  purification,  and  the  purification  of 
sewage,  are  all  treated  exhaustively  in  this 
Special  Report.) 

(d)  Twenty-Second  Annual  Report  con- 
tains additional  results   of   chemical   and 
microscopical  examinations. 

(e)  Many  of  the  earlier  reports  contain 
much  valuable  matter,  but  the  Nineteenth 
to  Twenty-Second  Annuals,  and  the  Special 
Reports  are  the  chief  references  for  the 
recent  views. 

14.  MacDonald,  J.   D. :  A  Guide  to  the 
Microscopical    Examination    of    Drinking 
Water.      2d  ed.,    8vo,  London,  J.  and  A. 
Churchill,  1883. 

15.  Mills,  H. :  Micro-Organisms  in  Buf- 
falo Water  Supply  and  in  Niagara  River. 
Proc.  Am.  Soc.  Micrs.,  1882. 

16.  Nichols,  Win.  Ripley :    (a)   On  the 
Filtration  of   Potable  Water.    Ninth  An. 
Rept.  Mass.  St.  Bd.  Health ;  also  reprint  by 
D.  Van  Nostrand,  New  York,  1879. 


144 

(£)  Eemarks  on  the  Tastes  and  Odors  of 
Surface  Waters.  Jour.  Assn.  Eng.  Socs., 
Jan.,  1882. 

(c)  Natural  Filtration  at  Berlin.     Jour. 
Frank.  Inst.,  CXIIL  (1882),  pp.  209-216. 
(This  paper  contains  an  account  of  Creno- 
tkrix,  and  a  number  of  references  to  the 
literature  of  that  organism.**) 

(d)  Water    Supply    considered    Mainly 
from  a  Chemical  and  Sanitary  Standpoint. 
**  8vo,  New  York,   J.    Wiley  and   Sous, 
1883. 

17.  Parkes,  E.  A. :  A  Manual  of  Prac- 
tical Hygiene.     2  vols.  in  1,  8vo.     From 
last  London  ed.,    New  York,  Win.  Wood 
&  Co.,  1884.    (Contains  an  appendix  giving 
the  American  practice.) 

18.  Parkes,    L.    C. :    Hygiene   and    the 
Public    Health.      12mo,    Philadelphia,    P. 
Blakiston,  Son,  &  Co.,  1889. 

19.  Radlkofer,  L. :  Mikroscopische  Un- 
tersuchung    der    Organischen    Substanzen 
im  Brunnenwasser.     Zeitschrift  fur  Biolo- 
gie,  1865. 

20.  Rafter,  G.   W.  :  (a)   On  the    Micro- 
Organisms  in  Hemlock  Water.    Rochester, 
1888. 


145 

(b)  On  the  Fresh-Water  Algae  and  their 
Relation  to  the  Purity  of  Public  Water 
Supplies.      Trans.  Am.    Soc.  C.  E.,  XXL 
(1889),  pp.  483-557. 

(c)  Biological  Examination   of   Potable 
Water.     Prod.  Roch.  Acad.  Sci.,  1890,  pp. 
34-44. 

(d)  Deterioration  of   Water   in    Reser- 
voirs;  its  Causes  and  Prevention.     Four- 
teenth   An.    Rept.    Xew    Jersey    St.    Bd. 
Health,  1890,  pp.  111-122. 

21.  Sedgwick, -Win.  T. :  (a)  Recent  Prog- 
ress in  Biological  Water  Analysis.     Jour. 
New  Eng.  W.  Wks.  Assn.,  Sept.,  1889.  pp. 
50-55. 

(b)  Utilization    of    Surface    Water   for 
Drinking  Purposes.     Jour.  New  Eng.  W. 
Wks.  Assn.,  Sept.,  1890,  pp.  33-39. 

(c)  The  Data  of  Filtration  :  Part  I.,  Bac- 
teria in    Drinking   Water.      Part    II.,  Oii 
Crenothrix    Kiihnina    (Rabenhorst)    Zopf, 
Tech.  Quart.,  Mass.  Inst.  Tech.,  1890. 

(d)  Report  as  Biologist,  in  Special  Rept. 
Mass.  Bd.     (Noted  under  Mass.  Repts.) 

22.  Smart,    C. :    Report   on    the    Water 
Supply  of  Mobile  and  New  Orleans.    Rept. 
Nat.  Bd.  Health,  1880,  pp.  441-514. 


146 

23.  Sorby,  H.  C. :  Detection  of  Sewage 
Contamination  by  the  Use  of  the  Micro- 
scope and  on  the  Purifying  Action  of  Mi- 
nute Animals  and  Plants.    Jour.  Soc.  Arts, 
XXXII.   (1884),  pp.  929-930 ;  Jour.  Eoy. 
Micr.  Soc.,  Ser.  II.,  vol.  iv.  (1884),  pp.  988- 
991. 

24.  Tiemann    and    Gartner :    Die    Che- 
inische    und      Mikroskopisch-Bakteriolo- 
gische  Untersuchung  cles  Wassers.      8vo, 
Braunschweig,  F.  Viemeg  and  Son,  1889. 

25.  Vorce,    C.    M. :    Microscopic    Forms 
Observed  in  Water  of  Lake  Erie.     Proc. 
Am.    Soc.    Micrs.    for  the   year   1881  and 
1882. 

26.  Wanklyn,   J.  A.  :    Water   Analysis. 
12mo,    7th   ed.,   !N"ew  York,  D.  Van  Nos- 
trand  Co.,  1889. 

27.  Wilson,    G. :    A    Handbook    of    Hy- 
giene  and   Sanitary   Science.      12mo,  5th 
ed.,  Philadelphia,  P.  Blakiston,  Son,  &  Co., 
1885. 

28.  Wolff,  A.  J.  :  The   Sanitary  Exam- 
ination of  Drinking  Water.     Eighth  An. 
Kept.  Conn.   St.    Bd.    Health   (1885),    pp. 
251-305. 


147 

29.  Zopf,  W. :  Entwickehmgsgeschlicht- 
liche  Untersuchung  iiber  Crenothrix  Poly- 
spora,  die  Ursache  der  Berlin  Wassercala- 
mitat.  Berlin,  1879. 


II.  GENERAL    BOTAXY. 

30.  Bessey,    C.  F.  :    Botany    (Advanced 
Course),  8vo,  5th  ed.,  New  York,  Henry 
Holt&  Co.,  1888.' 

31.  Gray,  A. :  Structural  and  Systematic 
Botany  and  Vegetable  Physiology.     8vo. 

32.  Sachs,  J.:  (a)  Text-Book  of  Botany.** 
Edited   by   Vines.      8vo,   2d   ed.,   Oxford, 
Clarendon  Press,  1882.     (b)  Physiology  of 
Plants.**     8vo,  Oxford,  Clarendon  Press, 
1887. 

III.  CRYPTOGAMIC    BOTAXY. 

33.  Bennett   &    Murray :    A   Handbook 
of    Cryptogamic    Botany.**     12mo,    New 
York,  Longmans,  Green,  &  Co.,  1889. 

34.  Grevilea :     A  Quarterly    Eecord   of 
Cryptogamic  Botany,  1872-1886. 


148 


IV.  —  FRESH-WATER 

35.  Cooke,  M.  C.  :  British  Fresh-  Water 
Algae,    exclusive   of    the    Desmidiea?   and 
Diatomaceae.**     2  vols,  8vo,  London,  Wil- 
liams &  Norgate,  1882-1884 

36.  Hassali,  A.  H.  :     A  History  of  the 
British  Fresh-  Water  Algae,  including  Des- 
midieae    and    Diatomaceae.      2   vols,    8vo, 
London.  1857. 

37.  Rabenhorst,  L.  :  Flora  Europaea  Al- 
garum  Aquae  Dulcis  et  Submarine.**     8vo, 
Leipsic,  1864. 

38.  Wolle,    F.  :    Fresh-  Water    Algae    of 
the    United    States.**      8vo,    Bethlehem, 
Pa.,  1887. 

39.  Wood,  H.  C.  :  A  Contribution  to  the 
History  of  the  Fresh-Water  Algae  of  North 
America.**     4to,  Washington,  1872. 

V.  —  DESMIDIE.E. 

40.  Cooke,   M.   C.  :    British  Desmids,   a 
supplement  to  British  Fresh-  Water  Algae. 
8vo,  London,  Williams  &  Norgate,  1886, 
1887. 

41.  Ralfs,  D.  :  The  British  Desmidiese. 
8vo,  London,  1848. 


149 

42.  Wolle,  F.:    Desmids  of   the  United 
States.**     8vo,  Bethlehem,  Pa.,  1884. 

VI. DIATOMACE^E. 

43.  Habirshaw,  F. :  Catalogue  of  the  Dia- 
tomacese.     With  references  to  the  various 
published  descriptions  and  figures.     New 
York,  1877. 

44.  Smith,  Win. :     Synopsis  of  the  Brit- 
ish  Diatomacese.      2   vols.    8vo,    London, 
1853-1856. 

45.  Smith,  H.  L.  :  A  Contribution  to  the 
Life  History  of   the    Diatomacese.     Proc. 
Am.  Soc.  Micrs.,  1886,  1887. 

46.  Van  Heurck.  H. :  Synopses  des  Di- 
atomees   de  Belgique.**     2  vols.  8vo,  An- 
vers,  1885. 

47.  Wolle,    F. :    Diatomaceae   of    North 
America.**     8vo,  Bethlehem,  Pa.,  1890. 

VII. —  FUNGI. 

48.  Cooke   &   Berkeley:    Fungi:    Their 
Nature,  Influence,  and   Uses.     3d  ed.,  12- 
mo,  London,  Kegan,  Paul,  Trench,  &  Co., 
1883. 


150 

49.  Crookshank,  E.  M.  :  Manual  of  Bac- 
teriology.**     3d   ed.,  8vo,  New  York,  D. 
H.  Vail  &  Co.,  1891. 

50.  De   Barry,    A. :     Comparative    Mor- 
phology and  Biology  of  the  Fungi,  Myce- 
tozoa,  and  Bacteria.**     8vo,  Oxford,  Clar- 
endon Press,  1887. 

51.  Mathews    &  Lott :    The   Microscope 
in   the   Brewery  and   Malt  House.      8vo, 
New  York,  I).  Appleton  &  Co.,  1889. 

52.  Pasteur,    L. :     Studies    on    Fermen- 
tation.     8vo,  London,   Macmillan   &    Co., 
1879. 

53.  Schiitzenberger,  P. :    On    Fermenta- 
tion.     12mo,  New  York,  D.  Appleton   & 
Co.,  1889. 

VIII. GENERAL    ZOOLOGY. 

54.  Brooks,  W.  K. :  Handbook  Inverte- 
brate Zoology.     8vo,  Boston,  1882. 

55.  Clauss,   C.  :     An   Elementary  Text- 
Book    of    Zoology.      2  vols.  8vo,  London, 
Macmillan  &  Co.,  1885. 

5G.  Huxley,  T.  H. :  Manual  of  the  Anat- 
omy of  Invertebrated  Animals.  8vo, 
1877. 


151 


IX. MICROSCOPICAL    CRUSTACEA. 

57.  Baird,  W. :     The  Natural  History  of 
the  British  Entomostraca.**    8vo,  London, 
Ray  Society,  1850. 

58.  Herrick,  C.  L. :  (a)  Microscopic  En- 
tomostraca.     An.  Rept.  of  the  Geolog.  and 
Nat.   His.  Sur.    Minn.,    1878,   pp.  81-123T 
21  Plates. 

(b)  A  Final  Report  on  the  Crustacea  of 
Minnesota,  included  in  the  Orders  Cla- 
docera  and  Copepoda.**  Geol.  and  Nat. 
His.  Sur.  Minn.,  30  Plates,  Minneapolis, 
1884. 

X. ROTIFERA. 

59.  Herrick,  C.  L. :  Notes  on  American 
Rotifera.     Bull.  Sci.  Lab.  Dennison   Uni- 
versity, pp.  43-62,  Granville,  Ohio,  1885. 

60.  Hudson  and    Gosse :    The  Rotiferru 
or  Wheel    Animalcules,  both  British  and 
Foreign.**      Roy.  8vo,  2  vols.  with   Sup- 
plement,   London,    Longmans,    Green,  .  & 
Co.,  1889. 


152 


XI. —  POLYZOA. 

61.  Allman,  G.  J. :  The  Fresh-Water 
Polyzoa.**  Fol..  London,  Ray  Society,  1856. 

02.  Hyatt,  A. :  Observations  on  Poly- 
zoa.** Proc.  Essex  Inst.,  IV.  and  V., 
Salem,  1866-1868. 

63.  Stokes,  A.  C. :  The  Statoblasts  of 
our  Polyzoa.  The  Microscope,  IX.,  1889. 


XII. INFUSORIA. 

64.  Kent,    W.    S.  :    A    Manual    of    the 
Infusoria.**      2  vols..  Roy.    8vo,  London, 
David  Bogue,  1880.  1881. 

65.  Pritchard,    A. :  A  History  of   Infu- 
soria, including  the  Desmidiaceae  and  Dia- 
tom acese.**     (Also  includes  the  Rotifera.) 
4th  ed.,  8vo,    London,  Whittaker  &   Co., 
1861. 

66.  Stokes,  A.  C.  :  A  Preliminary  Con- 
tribution towards  a  History  of  the  Fresh- 
Watea'   Infusoria,   of    the    United    States. 
Jour.   Trenton    Nat.    His.    Soc.,    I.,    1888, 
pp.  71-344.     13  Plates. 


153 


XIII. RHIZOPODS. 


67.  Leidy,  J. :  Fresh-Water  Rhizopods 
of  North  America.**  Published  by  U.  S. 
Geol.  Sur.,  4to,  Washington,  1879. 


XIV. — SPONOIDJE. 

68.  Bowerbank,  J.   S. :    (a)    Monograph 
of  the  Spongillidse.**      Proc.  Zool.    Soc., 
London,  1863.     (b)  On   the  British  Spon- 
giadae.**      3    vols.,    London,    Eay     Soc., 
1864-1874. 

69.  Carter,  J.   S.  :    History  and    Classi- 
fication of  the  Known  Species  of  Spongil- 
la.**     Anns,  and  Mag.  Nat.  His.,  London, 
1881. 

70.  Mills,    H. :    Fresh- Water    Sponges. 
Proc.  Am.  Soc.  Micrs.,  1882-1884-1888. 

71.  Potts,  E.  :   Contributions  towards  a 
Synopsis  of  the  American  Forms  of  Frebh- 
Water  Sponges,  with  Descriptions  of  those 
named  by  other  Authors,  and  from  all  pai-ts 
of  the  World.  Proc.  Acad.  Nat.  Sci.,  Phila- 
delphia, Pt.  II.,  Apr.-Aug.,  1887,  pp.  15S- 
279.    8  Plates. 


154 

XV GENERAL    PHYSICS. 

72.  Deschamel,  A.  P. :  Elementary  Trea- 
tise  on   Natural   Philosophy.     8vro,   New 
York,  D.  Appleton  &  Co.,  1875. 

73.  Ganot,    A. :    Traite   Elementaire  de 
Physique.     12mo,  Paris,  1868. 

74.  Jamin,  M.  J. :  Cours  de  Physique  de 
PEcole    Polytechnique.      4    vols.,    Paris, 
1883. 

XVI. LIGHT    AND    ITS    RELATIONS. 

75.  Koscoe,  H.  E. :  Spectrum  Analysis. 
4th   ed.,  8vo,  London,   Macmillan    &    Co., 
1885. 

76.  Schellen.   H. :   Spectrum  Analysis. 
2d   ed.,    8vo,    London,  Longmans,    Green, 
&  Co.,  1885. 

77.  Tyndall,    J. :     On    Light.     2d    ed., 
12mo,  New  York,  D.  Appleton  &  Co.,  1883. 

XVII. OPTICS. 

78.  Aedis,  W.  S. :  An  Elementary  Trea- 
tise on  Geometrical    Optics.     12mo,  Cam- 
bridge, Deighton,  Bell  &  Co.,  1888. 


155 

79.  Glazebrook,  K.  T. :  Physical  Optics. 
12mo,   New   York,    D.    Appleton    &    Co., 
1883. 

80.  Lardner,  D. :    Optics.      12mo,    Lon- 
don, Crosby,  Lockwood.  &  Co.,  1878. 

81.  Monckhoven,  D.  Van  :  Photographic 
Optics.      12mo,   London,    E.    Hardwicke, 
1867. 

82.  Parkinson.  S. :  A  Treatise  on  Optics. 
4th  ed..  12mo,  London,  Macmillan  &  Co., 
1884. 

XVIII. THE     MICROSCOPE    AND    MICROSCOP- 
ICAL TECHNOLOGY. 

83.  Bausch.  E. :    Manipulation  of   the 
Microscope.     16mo,  Rochester.  1885. 

84.  Beale,  L.  S.  :  (a)  How  to  work  with 
the  Microscope.*  *      5th   ed.,    8vo,    Phila- 
delphia, Lindsay  &  Blakiston,  1880. 

(b)  The  Microscope  in  Medicine.  4th 
ed.,  8vo,  Philadelphia,  Lindsay  &  Blakis- 
ton, 1878. 

85.  Behrens,  J.  W.  :    A  Guide  for  the 
Microscopical    Investigation  of  Vegetable 
Substances.*  *     8vo,  Boston,  S.  E.  Casino 
&  Co.,  1885. 


156 

86.  Carpenter,  W.  B.  :  The  Microscope 
and    its    Bevelations.*  *      6th    ed.,    12mo, 
London,  J.  and  A.  Churchill,  1881. 

87.  Cole,  A.  C.  :  Studies  in  Microscop- 
ical  Science.     2  vols.,  8vo,  London,  Bail- 
Here,  Tindall,  &  Cox,  1883. 

88.  Davis   &  Mathews :    The    Prepara- 
tion and  Mounting  of  Microscopic  Objects. 
New  York,  G.  P.  Putnam's  Sons,  1890. 

89.  Davis,  G.  E.  :  Practical  Microscopy. 
2d  ed.,  8vo,  London,  David  Bogue,  1882. 

90.  Frey,    H.  :     The    Microscope    and 
.Microscopical    Technology.*  *     8v"o,   New 
York,  Win.  Wood  &  Co.,  1880. 

91.  Gage,  S.  H.  :  (a)  Notes  on  Micro- 
scopical   Methods.       8vo,    Ithaca,     N.  Y., 
Andrus  &  Church,  1886-7. 

(b)  Notes  on  Histological  Methods.*  * 
8vo,  Ithaca,  N.  Y.,  Andrus  &  Church, 
1885-6. 

92.  Hogg,    J.  :    The    Microscope :    Its 
History,    Construction,    and    Application. 
12th  ed.,  12mo,   London,  G.  Routledge  & 
Sons,  1887. 

93.  Journals. 

(a)  The  Am.  Jour.  Microscopy,  1876- 
1881. 


157 

(b)  The  Am.  Monthly  Micr.  Jour.,  1880- 
1891. 

(c)  Jour,  de  Micrographie,  Paris,  1877- 
1891. 

(d)  Jour.  Hoy.  Micr.  Soc.,  London,  1878- 
1891. 

(e)  Monthly  Micr.  Jour.,  London,  1869- 
1877. 

(/)    The  Microscope.  1881-1891. 

(g)  Quarterly  Jour.  Micr.  Soc.,  London, 
1853-1868. 

(h.)  Zeitschrift  fiir  Wissenschaftliche 
Mikroskopie  und  fur  Mikroskopische  Tech- 
nik.  Braunschweig,  1885-1891. 

94.  Griffith  and  Henfrey  :    The  Micro- 
graphic  Dictionary.     4th  ed.  Svo,  London, 
J.  Van  Voorst,  1883. 

95.  Naegeli  &  Schwendener :  The  Mi- 
croscope   in  Theory   and   Practice.      8vo, 
London,    Swan,    Sonnenschein,    Lowry,  & 
Co.,  1887. 

96.  Nave,  J.  :  Collector's  Handy-Book. 
16mo,  London,  W.  H.  Allen  &  Co. 

97.  Queckett,  J.  :  A  Practical  Treatise 
on   the  Use   of   the  Microscope.      3d  ed., 
8vo.,  London,  H.  Bailliere,  1855. 


158 

98.  Van   Heurck,  H. :    Le  Microscope, 
sa    construction,    son    maniement,   et   son 
application  speciale  a  Panatomie  vegetale 
et  aux  diatomees.     3d  ed.,  Bruxelles,  1878. 

XIX. MISCELLANEOUS,     INCLUDING     JOUR- 
NALS OF  BIOLOGY  AND  ZOOLOGY. 

99.  Braun,  A.  :  Eejuvenescence  in  Na- 
ture.    8vo,  London.  Ray  Society,  1853.  ; 

100.  Cooke,  M.  C.  :   (a)  One  Thousand 
Objects  for  the  Microscope.     16mo,  Lon- 
don. F.  Warne  &  Co. 

(Ij)  Ponds  and  Ditches.  16mo,  London, 
1885. 

(c)  Rust,  Smut,  Mildew,  and  Mould  :  An 
Introduction  to  the  Study  of  the  Micro- 
scopic Fungi.  5th  ed.,  12ino,  London, 
W.  H.  Allen  &  Co.,  1886. 

101.  Huxley  and  Martin :  A  Course  of 
Elementary   Instruction   in   Practical   Bi- 
ology.    12m o,  London,   Macmillan  &  Co., 
1883. 

102.  Journals  of  Biology  and  Zoology. 
(a)    American    Naturalist.    Salem    and 

Philadelphia,  1867-1891. 


159 

(#)   American  Society  of  Microscopists, 
Proceedings,  1879-1891. 

(c)  Archives  de   biologie,   Paris,  1880- 
1891. 

(d)  Archives  de  zoologie  experimentale 
et  generale,  Paris,  1883-1891. 

(e)  Mittheilungen  aus  der  zoologischen. 
Station  zu  Neapel,  zugleich   ein  Keperto- 
rium  fiir  Mittelmeerkunde.     Leipsic,  1878, 
1891. 

(/)    Zeitschrift  fiir   Biologic.     Munich, 
1865-1891. 

103.  Lankester,  E. :    Half-Hours    with 
the   Microscope.     17th  ed.,  16mo,  London, 
W.  H.  Allen  &  Co.,  1890. 

104.  Queckett,  J.  :  Lectures  on  Histol- 
ogy.    (Elementary  Tissues  of  Plants  and 
Animals.)     2  vols.  8\ro,  London,  H.  Bail- 
Here,  1852. 

105.  Sachs,  J.  Von  :  History  of  Botany 
(1530-1860).      12mo,    Oxford,    Clarendon 
Press,  1890. 

106.  Sedgwick    and  Wilson  :    General 
Biology,  Part  I.     8vo,  New  York,  H.  Holt 
&  Co.,  1888. 

107.  Strasburger,  E.  :  Microscopic  Bot- 


160 

any :     A   Manual   of    the    Microscope   in 

Vegetable  Histology.     8vo,  Boston,  S.  E. 
Casino,  1887. 

108.  Taylor,    J.    E.  :    The    Aquarium. 
Its    Inhabitants,  Structure,    and    Manage- 
ment.    London,  W.  H.  Allen  &  Co.,  1884. 

109.  Tyndall,  J. :  Essays  on  the  Float- 
ing Matter  in  the  Air,  in  Relation  to  Putre- 
faction and   Infection.      8vo,  ^"ew  York, 
D.  Appleton  &  Co.,  1884. 

110.  Wood,  J.  G.  :  Common  Objects  for 
the  Microscope.     16mo,  London,  G.  Rout- 
ledge  &  Sons. 


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